Can you remind us what the levels of REL are?
Regular REL is for events ranging from casual drafts to prereleases to FNM to game day. Regular REL events don’t require a judge and are focused on fun and community and education for the most part. There are no harsh penalties at this rules enforcement level, but certain behaviours are always unacceptable and you can be removed from an event for doing them.
Competitive REL is for events like PPTQs, SCG IQs, and similar events all the way up to the Saturday or a Grand Prix. Competitive REL events require judges and feature bigger prizes and qualification to exclusive events. Rules enforcement at these events is stricter, with a greater focus on correct play and clear communication between players. Competitive REL features a full range of penalties up to and including disqualification.
Professional REL is used at the Pro Tour and on later days of other premier events like Grand Prix Sundays and the World Championships. There are only a few differences between Professional REL and Competitive REL, and they keep getting smaller every year. Just act as you’re expected to act at Competitive REL and you’ll be fine.