This patch resolves the issue mentioned in T8298 - Geary 3.32.1 high cpu due to upstream bug
Geary can continuously use all available cpu due to an upstream bug in handling some UTF in a mail header string
This is described here: https://gitlab.gnome.org/GNOME/geary/issues/504
A patch for the current mainline has been provided and was merged into mainline:
I have cherry picked this commit into tags/geary-3.32.1 which applied without issue.
From there I created a patch file which I added to the solus geary build as a patch.
This builds cleanly and resolves the issue for me.