Usual caveat - there are very few (ie. none) regular MacOS users who visit this forum. This an older Mac VM and a Gimp 2.10.10
I can see the problem: this for reference:
(1) I can apply script-fu filters, the above has had guides-by-percent added followed by the coffee-stain filter. They both worked.
(2) Minimizing Gimp there is indeed the last used script-fu filter hiding behind Gimp on the desktop.
(3) The only way I could get a second script-fu icon showing is open the script-fu terminal, but that closes when I close the terminal.
Trying python plugins (heal-selection) and the newer GEGL filters and they worked as I would expect. Nothing left behind.
Is it a big problem ? The running script-fu (and icon) closes when you close Gimp.
I am 99% not familiar with MacOS Maybe you can explain. A right click on the script-fu icon gave an option to "show all windows" and it does show the script-fu window. However that also seems to close it, repeated the process and got a 'no windows to show'. However the icon is still there in the toolbar.
I would say it is probably a bug, that not-responding you reported is there. You can report bugs at
https://gitlab.gnome.org/GNOME/gimp/-/issues Is it worth the effort ? The developers use linux. There seems to be one person who compiles the MacOS version and they are missing-in-action at the moment.