When applets start to wander around that is because the panel gsettings info has become corrupted.
Usually this happens if you uninstall an applet that was expected in a layout, logout and login. Once done there isn’t a way back to resolve… even if you reinstall the applet again.
Occasionally the panel can become corrupted if you have had a whole session crash or you have unexpectedly powered off your machine … e.g. running out of battery power.
Basically the only way to recover is to reset the panel back to its defaults and redo your config again.
nohup budgie-panel --reset --replace &
Note you can backup your panel settings ab restore again if it messes up again.