Hi @carolinemayou ,
How do you customize the form for your CRM Entity? Using classic experience or New experience in PowerApps?
Do you mean that the error would show up when you publish the form? Does it show up when save your form?
Based on the issue that you mentioned, I have made a test on my side, and don't have the issue that you mentioned. Please consider clear cache of your browsers, then try it again, then check if the issue is solved.
Also please consider take a try to edit the form of CDS Entity (CRM Entity) within PowerApps using New experience:

Please also make sure the Network state is in good condition on your side.
Best regards,