It is probably the Raspberry Pi part of the equation. Debian should be ok.
I would report the issue to the Gimp devs.
EDIT: As far as I know, only one other post about that mix from member Teapo
Edit again: Looks like teapot has reported this bug. https://gitlab.gnome.org/GNOME/gimp/-/issues/15552 no fix as yet but is coming. Guessing that was your post there.
I would report the issue to the Gimp devs.
EDIT: As far as I know, only one other post about that mix from member Teapo
Edit again: Looks like teapot has reported this bug. https://gitlab.gnome.org/GNOME/gimp/-/issues/15552 no fix as yet but is coming. Guessing that was your post there.