I have documented workarounds at https://daniel-lange.com/archives/195-Getting-scanning-to-work-with-Gimp-on-Trixie.html
You have the choice between a Python script by Lee Yingtong Li (RunasSudo) or compiling the latest upstream which has the Gimp 3.x compatibility patches.
I hope a new upstream xsane will be made available some time later via trixie-backports.
