Arrowverse is only ONE universe within the larger DC live-action multiverse. Arrowverse is a nickname for the CWuniverse of shows, not the entire DC live-action multiverse. The Arrowverse MAY eventually include Stargirl now that they are on the same network, similar to how they eventually incorporated Supergirl and Black Lightning, but that remains to be seen. Arrowverse is still a separate universe from DCEU, Christopher Reeve's Superman Universe, Smallville, Burton's Batman, etc. The entire DC multiverse doesn't revolve around the Arrowverse just because there was a brief crossover with other separate DC universes. If you don't believe me, ask Jim Lee. They just explained the Multiverse during Fandome. Arrowverse is part of it, just like every other live-action film and movie. They exist at the same time, but in their own universes.