I have a few forms where a field has a dropdown option but the arrow is appearing outside the field box.
Also where i have a postcode option on the address field there is also a dropdown arrow appearing where there shouldn’t be because its a field that has to typed for example.
I would recommend you to try the form using the Preview button you can find on the form editor screen. That will show you the form using default Gravity Forms styling, if the form looks ok using preview, that would indicate something else in your site setup is causing the issue (probably the theme or builder if you’re using one).
If you’re still able to replicate the issue using the Preview, I would recommend you to open a ticket.