Upgrading any software aften introduces bugs – alongside the fixes and Flutter 3.27 is no different – introducing issues in TextFormField on the web Platform.
The TextFormField web issues
There are probably more.
Temp Solution
In my experience forcing the Flutter Engine to use WASM as the Web Target silenced the problem.
Long Term Fix
If you want long term resolution – upvote the issues, comment and be out-spoken about it, so the noice to reach the Flutter Engine Developers at Google. And – Be polite. They are doing a lot for us all.