A new rebuild is needed:

XPCOMGlueLoad error for file /usr/lib/icedove/libxul.so:
libicui18n.so.67: cannot open shared object file: No such file or directory
Couldn't load XPCOM.

Installing icu-compat-67 works around it for the time being.

just to note, that i tried many times with multiple versions (68
78, 91), but could get none to compile - this program is always
troublesome

the abslibre 'wip-icedove' branch shows what ive tried so far
https://git.parabola.nu/abslibre.git/log/?h=wip-icedove

for the amount of effort required, and that it spends more
days behind arch than not, we should consider dropping it -
perhaps someone from the community wants to maintain it, in the
way that grizzlyuser has been maintaining iceweasel?

icedove has been broken since before the new 'icu' this week (#3115) - i tried several version combinations of LLVM/clang, gcc , rust (1.44.1, 1.52.1, and current), and mozilla (68, 78, 91), all unsuccessfully

FWIW, arch32 is still at v68; because they can not get it to build either

currently, any successful icedove build closes both tickets