Hi KC,
Thanks for feedback. I can reproduce this issue on my side.
On PowerApps studio for Web, add a DataTable control to a DataCard in an EditForm. Set the data source of the DataTable to a SharePoint list, add one field from Property Panel Data Tab, everything seems fine.
An error would occur if you are trying to add another field or even change to another field.

On PowerApps studio for Windows, with the same steps, the app would be closed without any warning.
I will try to report this issue on my side and back to you once I got any response.
Best regards,
Mabel Mao