I think the first two, and even arguable about second. Look at title winning squads of Real Madrid under Ancelotti. Squad depth = check. Tactics? None lol. And look at PSG winning Ligue 1 (during Mbappe time). Squad depth = check. Tactics? None.
These teams won everything with depth and talent. But they were opened up big time when they actually played teams with tactics.
Barca = financial stability, ZERO. We still won La Liga.
PSG already have deep squad and their success last season proves it so well but defending titles especially big and hard to win title like UEFA Champions League is very difficult. In Champions League history, only Real Madrid succeeded to defend their crown and PSG will be a second champion can defend their title. I believe PSG are able to go very far in Champions League but to win this title again, it won't be too easily not only for PSG but for any club. They might win it again, but not in a next season and they can win it like how Chelsea did it in two different seasons that far with each other in time.
Mbappe was a big issue of PSG as with him, their squad lacked of proactive defense contributions from him, and let's review this difference between Mbappe (seasons ago) and Dembele (last season).