Why were the temporal police so concerned with Janeways earlier infractions but totally left her alone when she came back to rescue voyager earlier, turbo fucked the borg and brought future tech with her in the finale? Any fun headcanons or observation there?
All they care about is the general well-being of the temporal federation. Perhaps it's so difficult and wiggly wobbly that it's worthwhile letting one of your temporal agents languish in the 1900s for decades if in the end it works out for the timeline. Especially if strange circumstances somehow strengthen their position in the temporal wars.
Or the borg achieving time travel tech was an inevitability and Janeway destroying them was a necessity to keep the borg from assimilating all life in a manner similar to First Contact (thus negating the existence of the temporal police).
Because they're more concerned with the Federation continuing to exist as a major player in the galaxy than they are with the timeline remaining unblemished. For whatever reason, Voyager getting home early is better than the alternative.
I think the scale of change, and also displacement, are both factors. Going back 3 days to change who wins a bet isn’t going to piss off the temporal police. Maybe going back and fucking with your own timeline a bit is the same. Maybe that’s why Red Foreman got away with his shit even when it started to impact humans.