label column filled when using `Hmisc::rcspline.eval()` and `poly()` , but not for other categorical variables about broom.helpers HOT 2 CLOSED

library(broom.helpers)
library(gtsummary)

mod <- glm(age ~ grade + Hmisc::rcspline.eval(marker), data = trial, family = gaussian)

mod %>%
  tidy_and_attach() %>%
  tidy_identify_variables() %>%
  tidy_add_variable_labels() %>%
  tidy_add_reference_rows() %>%
  tidy_add_header_rows() %>%
  select(1:2, label)
#> # A tibble: 9 x 3
#>   term                       variable                  label                    
#>   <chr>                      <chr>                     <chr>                    
#> 1 (Intercept)                <NA>                      (Intercept)              
#> 2 <NA>                       grade                     Grade                    
#> 3 grade_ref                  grade                     I                        
#> 4 gradeII                    grade                     II                       
#> 5 gradeIII                   grade                     III                      
#> 6 <NA>                       Hmisc::rcspline.eval(mar~ Hmisc::rcspline.eval(mar~
#> 7 Hmisc::rcspline.eval(mark~ Hmisc::rcspline.eval(mar~ Hmisc::rcspline.eval(mar~
#> 8 Hmisc::rcspline.eval(mark~ Hmisc::rcspline.eval(mar~ Hmisc::rcspline.eval(mar~
#> 9 Hmisc::rcspline.eval(mark~ Hmisc::rcspline.eval(mar~ Hmisc::rcspline.eval(mar~