I do hear you. And I appreciate you coming at it from a place of curiosity and not just telling me I'm wrong.
For me, and apparently a number of the youtube people I generally watch, it lacked an emotional sense of resolution. Yes, the plot of "who built the TVA and can we kill them?" was largely resolved, but it wasn't resolved (for me) in a way that had emotional resonance. The characters are supposed to go through something over the course of a season, and while (assuming multiple seasons) they have much more to go through, there are mini arcs under their bigger arcs.
So, let's say look at their plot to resolve who is behind the TVA and how do we stop them. It has to matter to the character in a deeper way. For instance, if it ended up being a Loki that represented everything Loki really wanted (being the ultimate ruler and king living an empty existence) and Loki defeated him, that would have emotional resonance and demonstrated personal growth and change. But we ended up with Immortus. We, as fans, know who that is because we either read comics or we read the internet. So when we see Immortus, we're like "OH SNAP IT'S THAT GUY HOW COOL!" But Sylvie and Loki? They have no idea who he is. So they're just talking to some random dude as far as they're concerned. Sylvie killing some random dude has no emotional depth. Loki learning his lesson from some random dude has no meaning. So it feels empty and hallow from that perspective. So Sylvie's arc of finding freedom ends with her killing a stranger she'd never heard of and then we cut away and don't show anything about how that impacts her.
Then you have the side characters. Mobius's arc was that he was a blind TVA agent who never questioned things and just played his role and really fantasized about Jet Ski's for some reason. His arc was to gain independence and individualism and try to spread that to his fellow TVA slaves. The result? He has no idea about anything and he's just a brainwashed analyst or whatever again. No resolution, just a reset. Same with that hunter he was hanging with.
Renslayer? She was 100% devoted to the cause, even when it all came crashing down. Her resolution? Nothing. She steps through a portal and we have no idea what the hell happened. This alone is fine, since not every character needs resolution, but when it all adds up, it just feels meh.
I fully understand that other people might not and do not feel the same way. And I am cool with that. I loved the show in all, and I enjoyed many aspects of the finale, but I just couldn't connect with the ending at all and it left me feeling empty inside. In a way that WandaVision and FATWS (who also had flawed endings) did not make me feel.
Hopefully that made sense.