I see that Plasmafox still sits at version 83.0 in the Chaotic repos.
This probably has nothing to do with the cleanup in Chaotic, but rather with a bug in the build process.
Effectively the build stalls at "Checking for otool..." in the configure part, preventing any rebuild. I don't know what exactly causes this as I had the same problem with vanilla Firefox from Arch, but the workaround is to kill the stalled process.
Therefore, I published precompiled binaries again, the most recent is here: Release 84.0.1-2 · torvic9/plasmafox · GitHub
(and don't forget the new public key)