If you vote on 24 answers during an SE network "day" on a site, then vote on a question, the following dialog comes up:
However, as indicated in the What are the limits on how I can cast, change, and retract votes? FAQ answer, you should still have 6 votes remaining. This is confirmed by the same dialog appearing again after the next post vote in that day. Note this problem doesn't occur if you've voted on at least one question within the initial 24 votes on that day.
This has happened to me several times on this site and on Stack Overflow, so it's apparently not site specific. Also, FWIW, I'm using a plain version (i.e., no add-ins, user scripts, etc.) of Edge on Windows 10.