We've fixed an issue affecting toggle buttons where validation rules were remaining in place after unchecking a toggle.
For an image field, if both 'Show the alt text field?' and 'Is the alt text required?' were set to 'Yes' initially, and then the first option was then set to 'No', the latter would then no longer be visible in the content type, but the validation would still apply i.e. alt text would still be required.