When adding a new translation: Deprecated function: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in Drupal\form_mode_manager_theme_switcher\Theme\FormModeThemeNegociator->isApplicable()

andreastkdf → changed the visibility of the branch 3486202-when-adding-a to hidden.

andreastkdf → changed the visibility of the branch 3486202-when-adding-a to hidden.

andreastkdf → changed the visibility of the branch 3486202-when-adding-a to active.

closing as Content Translation support ✨ Content Translation support RTBC is actually needed to even get to the translation form that has the issue.

Full error (sorry, missed the first bit in the previous comment)

Deprecated function: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in Drupal\form_mode_manager_theme_switcher\Theme\FormModeThemeNegociator->isApplicable() (line 93 of modules/contrib/form_mode_manager/modules/form_mode_theme_switcher/src/Theme/FormModeThemeNegociator.php).