From what they've said, they were actually hired to work on Baldur's Gate 4 and got partway through development but chose to stop because they didn't love having to stick with the D&D ruleset and preferred doing their own thing: https://www.pcgamer.com/games/baldurs-gate/larian-nearly-mad...
It's a shame, BG3 is one of my all time favourite games. But I really have to respect a company that can make a decision like this, leaving a super successful title behind as they feel it's not a good fit for the team.
