Bfmi-low problem with rstanarm after using parameters model_parameters

Greetings all,

I have a rather strange (may not be strange and it is my inexperiencedness) issue. After sampling via rstamarm, I use parameters package’s model_parameters to observe results. However, when I re-run the model for the second without any changes, I got;

Warning messages:
1: There were 1 chains where the estimated Bayesian Fraction of Missing Information was low. See
https://mc-stan.org/misc/warnings.html#bfmi-low 
2: Examine the pairs() plot to diagnose sampling pro

Is it a problem that I should be concerned?

m1 <- stan_glm(n~ -1 + Native_Language, family = neg_binomial_2(link = 'log'), init_r = 0.5, QR = TRUE, iter = 10000, prior_intercept = normal(2, 0.5), prior = normal(0, 2.5, autoscale = TRUE), data = alternation_freq)
> m1
stan_glm
 family:       neg_binomial_2 [log]
 formula:      n ~ -1 + Native_Language
 observations: 27
 predictors:   27
------
                                 Median MAD_SD
Native_LanguageBulgarian         5.1    0.9   
Native_LanguageChinese           4.7    0.9   
Native_LanguageChinese-Cantonese 6.1    0.9   
Native_LanguageCzech             5.1    0.9   
Native_LanguageDutch             5.3    0.9   
Native_LanguageFinnish           4.6    0.9   
Native_LanguageFrench            4.9    0.9   
Native_LanguageGerman            5.4    0.9   
Native_LanguageGreek             5.4    0.9   
Native_LanguageHungarian         4.9    0.9   
Native_LanguageItalian           5.1    0.9   
Native_LanguageJapanese          5.6    0.9   
Native_LanguageKorean            5.1    0.9   
Native_LanguageLithuanian        4.6    0.9   
Native_LanguageMacedonian        5.1    0.9   
Native_LanguageNorwegian         5.3    0.9   
Native_LanguagePersian           5.1    0.9   
Native_LanguagePolish            5.0    0.9   
Native_LanguagePortuguese        5.0    0.9   
Native_LanguagePunjabi           5.2    0.9   
Native_LanguageRussian           5.5    0.9   
Native_LanguageSerbian           5.3    0.9   
Native_LanguageSpanish           5.0    0.9   
Native_LanguageSwedish           5.4    0.9   
Native_LanguageTswana            5.4    0.9   
Native_LanguageTurkish           5.6    0.9   
Native_LanguageUrdu              4.8    0.9   

Auxiliary parameter(s):
                      Median MAD_SD
reciprocal_dispersion 1.4    0.9   

------
* For help interpreting the printed output see ?print.stanreg
* For info on the priors used see ?prior_summary.stanreg

So far so good. However;

x1_1 <- model_parameters(m1, centrality = "median", dispersion = FALSE, ci = .89, ci_method = "hdi", test = c("pd","ROPE", 'BF'),exponentiate = FALSE, diagnostic = "Rhat", priors = FALSE)
Sampling priors, please wait...
> x1_1
Parameter                        | Median |       89% CI |   pd | % in ROPE |  Rhat |     BF
--------------------------------------------------------------------------------------------
Native_LanguageBulgarian         |   5.06 | [3.59, 6.83] | 100% |        0% | 1.000 | > 1000
Native_LanguageChinese           |   4.72 | [3.22, 6.48] | 100% |        0% | 1.000 | > 1000
Native_LanguageChinese-Cantonese |   6.14 | [4.61, 7.90] | 100% |        0% | 1.000 | > 1000
Native_LanguageCzech             |   5.08 | [3.58, 6.93] | 100% |        0% | 1.000 | > 1000
Native_LanguageDutch             |   5.29 | [3.79, 7.13] | 100% |        0% | 1.000 | > 1000
Native_LanguageFinnish           |   4.61 | [3.16, 6.48] | 100% |        0% | 1.000 | > 1000
Native_LanguageFrench            |   4.94 | [3.42, 6.74] | 100% |        0% | 1.000 | > 1000
Native_LanguageGerman            |   5.39 | [3.84, 7.19] | 100% |        0% | 1.001 | > 1000
Native_LanguageGreek             |   5.37 | [3.90, 7.22] | 100% |        0% | 1.001 | > 1000
Native_LanguageHungarian         |   4.87 | [3.32, 6.58] | 100% |        0% | 1.000 | > 1000
Native_LanguageItalian           |   5.07 | [3.60, 6.82] | 100% |        0% | 1.000 | > 1000
Native_LanguageJapanese          |   5.58 | [4.11, 7.41] | 100% |        0% | 1.000 | > 1000
Native_LanguageKorean            |   5.12 | [3.61, 6.93] | 100% |        0% | 1.000 | > 1000
Native_LanguageLithuanian        |   4.60 | [3.11, 6.47] | 100% |        0% | 1.000 | > 1000
Native_LanguageMacedonian        |   5.09 | [3.64, 6.97] | 100% |        0% | 1.000 | > 1000
Native_LanguageNorwegian         |   5.26 | [3.75, 6.98] | 100% |        0% | 1.000 | > 1000
Native_LanguagePersian           |   5.08 | [3.63, 6.92] | 100% |        0% | 1.000 | > 1000
Native_LanguagePolish            |   5.02 | [3.55, 6.81] | 100% |        0% | 1.000 | > 1000
Native_LanguagePortuguese        |   5.01 | [3.52, 6.79] | 100% |        0% | 1.000 | > 1000
Native_LanguagePunjabi           |   5.15 | [3.71, 7.01] | 100% |        0% | 1.000 | > 1000
Native_LanguageRussian           |   5.47 | [4.00, 7.24] | 100% |        0% | 1.000 | > 1000
Native_LanguageSerbian           |   5.31 | [3.82, 7.12] | 100% |        0% | 1.000 | > 1000
Native_LanguageSpanish           |   5.02 | [3.57, 6.82] | 100% |        0% | 1.000 | > 1000
Native_LanguageSwedish           |   5.41 | [3.97, 7.25] | 100% |        0% | 1.000 | > 1000
Native_LanguageTswana            |   5.40 | [4.01, 7.25] | 100% |        0% | 1.000 | > 1000
Native_LanguageTurkish           |   5.56 | [4.09, 7.42] | 100% |        0% | 1.000 | > 1000
Native_LanguageUrdu              |   4.77 | [3.30, 6.61] | 100% |        0% | 1.000 | > 1000
reciprocal_dispersion            |   1.42 | [0.27, 3.12] | 100% |        0% | 1.001 | > 1000

Uncertainty intervals (highest-density) and p values (two-tailed) computed using a MCMC distribution approximation.
> m1 <- stan_glm(n~ -1 + Native_Language, family = neg_binomial_2(link = 'log'), init_r = 0.5, QR = TRUE, iter = 10000, prior_intercept = normal(2, 0.5), prior = normal(0, 2.5, autoscale = TRUE), data = alternation_freq)
Warning messages:
1: There were 1 chains where the estimated Bayesian Fraction of Missing Information was low. See
https://mc-stan.org/misc/warnings.html#bfmi-low 
2: Examine the pairs() plot to diagnose sampling problems
**sessionInfo()**
R version 4.1.1 (2021-08-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 22000)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                           LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] bayestestR_0.11.5 parameters_0.17.0 rstanarm_2.21.1   Rcpp_1.0.8.3      forcats_0.5.1     stringr_1.4.0     dplyr_1.0.8      
 [8] purrr_0.3.4       readr_2.1.2       tidyr_1.2.0       tibble_3.1.6      ggplot2_3.3.5     tidyverse_1.3.1   readxl_1.3.1