That's nothing new - maybe someone
could put a
warning for this in the opener to aviod old UnRen.
Pre 0.91 UnRen uses internal the old unrpyc version which is incompatible with RenPy versions after v7.1.? So decompiling is
a hard NO with old UnRen and
a maybe with v0.91 - if the games dev did not fuck around on the RPA or RPYC formats.
For manipulated RPYC we have the deobfuscate option of unrpyc which "Vespr" made recently available in a modded UnRen and for modified RPA unpacking i have my RpaKit tool most of the time up to date.

Greets