Hi Peter,
Just to let you know: using ReReplacer with J4, I had the following error when Saving after having added an emoji (from emojipedia) in the replacement text:
Save failed with the following error: 22007, 1366, Incorrect string value: '\xF0\x9F\x8E\xAC D...' for column `lejowspm_mFyAkHETp`.`4kl2_rereplacer`.`replace` at row 1
The tricky thing is: seeing thag error msg, I removed the emoji and could save.
Fine... except I had NOT noticed that the Regex Option which was set to YES had been set to NO because of this error.
So it took me time to understand why my replacement was not working anymore 🙂