- I reviewed a post, which was an audit.
- I was then given the message "Thank you for reviewing 20 Suggested Edits today."
Why does an audit count toward the maximum 20 reviews?
Because audits also count towards your review stats for badges as an action (assuming you passed). That means it could easily be abused by skipping all the normal posts and just keeping an eye out for audits, which would allow you to rack up a potentially infinite amount of actions without ever hitting a daily limit.
If you don't want audits to count towards the daily limit, then they can't count towards anything. It's one or the other; you can't have the best of both worlds.