I have an event that uses a price set and limits a price option in a price set to 7. Once it was reached, the event registration page results in WSOD. If I increase it, the page loads just fine. I recall this occuring to me months ago as well.
I am unable to properly test on https://wpmaster.demo.civicrm.org/ as it does not appear a registration in test mode counts against the participant count and I can't change this in the db directly. Is this just me or can others replicate?
Civi 5.35.2 WP 5.7.2
Ref: https://lab.civicrm.org/dev/core/-/issues?scope=all&state=opened&search=max+participant