I have had this happen twice. New user, no reviews in both instances.
Booking request came through for a day that was blocked. We have so many blocked days between each guest set up in our listing. Twice now, I have gotten a request to book (not an inquiry) for days that are not available. This latest was for a Thanksgiving check out. We have a check-in on the next day and no one is available on Thanksgiving day to clean or turn over, nor the day before. Not only should it be blocked per our time between guests I went in and made a note to myself on the day that no cleaners were available so I know it had the little "line" through it. Plus we are not doing back to back check ins right now due to COVID enhanced clean.
Did something change about the way Airbnb is allowing booking requests? I get inquiries all the time for days that are not available, but this is new for me to actually get booking request for one.
Inquiries and requests should be the same - are you referring to instant bookings? This has happened to me as well. when i have blocked days i have had guests trying to book those days but when they try to book a message will come through on my app letting me know so i can accept or decline. of course they are blocked so i decline. hope this helps, Good Luck!