The place to post that bug report is as Wallace's previous comment:
https://gitlab.gnome.org/GNOME/gimp/-/issues It might be one of those third-party plugins but the gimp devs are now making the flatpaks and should be interested.
Some things to look at:
What you have installed: In a terminal
flatpak list This is my Mint 22 VM
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The fourier plugin (FFT) is for Gimp 3 but is looking a bit old at gimp3rc1 but it does work. It is the version I prefer but there is also a FFT filter in the gmic plugin.
Sometimes you can get a clue by running Gimp in a terminal. For the flatpak it is
flatpak run org.gimp.GIMP Nothing much in my installation. Those resynthesizer script-fu's are probably in the scripts folder rather than plug-ins but the installation is well hidden in flatpaks.
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best of luck.