Due to how Firefox renders dropdown elements natively, placeholder text on dropdowns can't be changed conditionally. This is a browser-level limitation that Bubble can't override.
What you might notice
Conditional changes to a dropdown's placeholder text don't take effect on Firefox
The placeholder displays correctly on other browsers but remains static on Firefox
Workaround
There's no workaround for this specific Firefox behaviour. Consider displaying a dynamic label next to or above the dropdown instead, or design your UI so the dropdown placeholder doesn't need to change conditionally. You can read more in the documentation.
This is a browser-level limitation specific to how Firefox renders native dropdown elements.