A couple of things:

1) This is the first chapter of Phase 4 of the MCU and the first season of Loki. It can't be judged by itself as anything but an introduction. No conclusions have been drawn and none of the storylines have been resolved.

2) The TVA doesn't map directly to fascism because this is a fantasy show, not a documentary.

3) Literally every justification for the TVA's actions have turned out to be a lie. The Timekeepers, the origin of TVA personnel, nature of the "Sacred Timeline," etc. Taking anything stated by a TVA agent or its founder at face value isn't rational.

4) The reason that most of the TVA agents abandoned the cause is because they found their memories had been erased and they were literally different people. Renslayer didn't get her memories back or encounter her "real" identity. It seems like that's a core difference and possibly why her character didn't abandon the cause.

One can argue that this narrative element was an allegory for the personality changes as people go down the Q rabbit hole or invest in the hateful and fearful worldview of the Fox News Cinematic Universe, but that isn't stated onscreen. There is unfortunately no "quick fix" for those radicalized by right wing propaganda but I think expecting a Disney show to tackle that issue isn't really reasonable.

Personally, I have been impressed to date with the ambition of each MCU show on Disney+. People tuning in to see action and explosions have gotten them alongside shows about unresolved trauma, systemic racism, and now a treatise on free will vs fascism.

None of the three have been fully successful in my opinion but they're all quite good, and no one has ever tried anything like this before.