I've seen lots of people in the past asking why the Romulans stuck to the treaty after the Federation broke it, many seem to see it as a plothole. But really when you think about the realpolitik/geo galactic politics of it, it was a massive win for the Federation.
If the Romulans said "Hey this is bullshit! Our treaty is over!" then the Federation would just say "aight lmao, we'll just use this cloaking tech that's way better than yours. And it can be trivially retrofitted to existing ships, our whole fleet will have this tech."
By flexing that they can make this tech, it made clear to the Romulans that sticking to the treaty was something that was absolutely within their best interest, whereas before they weren't so sure about that. They thought they had a technological upper hand and were being hamstrung by their inability to fully leverage it to crush the Federation.
Bonus: it showed the Klingons that they too shouldn't provoke the Federation too much, nor should they try to destabilise relations between the Federation and the Romulans either, because if that treaty dies, they'd also lose what they thought was an advantage they had as well.
The whole thing was a staggering power-play by the Federation. They fulfilled the Speak softly and carry a big stick mantra perfectly.
It's such a crazy display on just how advanced the Federation really is that a small group of rogue Star Fleet officers were able to successfully leapfrog the cloaking tech to such a degree. There was another episode where the Romulans tried and failed to create that same technology but I can't remember if it was before or after Pegasus.
In DS9, a Vorta makes a comment about Star Fleet engineers being able to turn rocks into replicators and he really wasn't that far off.
If that phase cloak thing was attached to photon torpedoes it would make them invincible as well since they could phase back beyond enemy shields. Or inside the enemy ship.
Yes, that explains what Humans bring to the table: sheer, ill-informed, unbridled, un-jaded, undistilled, optimism.
It also explains why Voyager sports bio-neural components that can't handle cheese, why 1701-D is comically oversized compared to its crew compliment, why outfitting the entire Federation fleet with recycled Borg tech got the green light, and why bridge workstations have a failure mode that kills the operator with heavy-metal concert pyrotechnics the moment it's shaken too hard. Nobody told them they couldn't do that, so they did.