I'm having the same issue reported in this thread: Rich Text Editor Bug: null and "<p><br></p>"
Currently I am running Retool version 3.259.0 and when using an event to save data entered into the rich text field, it will randomly replace what was entered with
<p><br></p>
I can't reliably reproduce this, it's very intermittent
What I've done to fix this at the moment is to only allow my event to run if the richtexteditor.value !== "<p><br></p>"
Hopefully this helps if anyone else comes across this problem