This has been a problem for years, not just after the latest updates. There also aren't any "tone volume" settings with the original AirPods.
I managed to at least temporarily solve it by following two tips in this thread:
- Changing to the crickets ring tone.
- Adjusting the ring tone volume to minimum while a call was coming in.
There doesn't seem to be a separate ring volume setting for the built-in speakers and AirPods, it's the same slider. And even if you have a very moderate level set because of phone speakers, the volume is much louder with AirPods. I used to use the old telephone ring tone which was very loud when interrupting a podcast.
I could hear the ring tone volume change in real-time while adjusting the level when a call was coming in and just set it to minimum because that is the only really comfortable level for me. I usually keep my iPhone ringer muted anyway so it's not a big deal for me, but I can imagine if you need to keep a high level for the iPhone built-in speakers this isn't a complete solution.
Hopefully the volume level doesn't reset to a high level again later.