Actually, on trying it further, even the raw query mode for Firestore gives "where is not defined" errors even with static values in the where clause. I have no idea what's going on but whatever update y'all did broke it pretty bad.
Just to give an update on this issue, we were able to track down the cause of and submit a bug report with @icopps help. This was caused by a bug with Firebase queries when you switch between Raw mode and GUI mode: even after switching to GUI mode and making edits, the query was running what was set in raw mode.
Clearing inputs in raw mode and then switching to GUI mode should resolve this.
If anyone else is running into this issue, please try the above workaround, and if the problem persists write to our chat support and we would be happy to assist!