[2022] I started dungeon runs this season (just difficulty 1 so far). I can get to level 10,000 on some objectives but I'm limited to 1% max idol bonus.

It's a visual glitch with that display. You can see the amount of idols the area will give in the Rewards tab on the Dungeon dialog. Those are the numbers the server uses in the calculation when you reset the world.

We'll get that visual glitch fixed up.