From the mailing list thread:

For the record, those are all new packages (not orphaned packages being adopted). I assume more will come, we’ll clean those as soon as possible.

In the mean time stay vigilant, probably refrain from installing freshly pushed new packages from the AUR for now.

Looking over the list it’s almost all git/bin versions of files. So they just added a ton of new packages like hexchat-bin that didn’t have those versions before and injected malware.