The validation JS that's listening to "change" events is causing issues with the latest JCE versions. If you switch JCE to "source code" mode, the validation script is reacting to each and every keystroke, even escaping < and > characters and moving those into a new paragraph - that renders the code mode completly unusable, see:
https://djumla.dev/Voila_Capture%202022-06-24_10-32-14_AM.mov