Engine frequently turning on during braking on gen 4

I’m hoping to get some insight from others who are familiar with the Gen 4 Prius behavior, because something doesn’t feel quite right compared to what I’ve experienced before on previous generations.

I just picked up a 2017 Prius (Gen 4) with approximately 130k miles, and I’ve noticed that the engine will frequently start while I’m braking, even in situations where I wouldn’t expect it to. A good example is coming off the highway: the engine is already fully warmed up, and the battery state of charge is sitting around 5–6 bars out of 8. I’ll be decelerating normally, and instead of staying in regen like I’d expect, the ICE kicks on at idle RPMs and will stay running for about 30 seconds or so, even after coming to a stop.

What’s odd is that I’ve owned both a Gen 2 and a Gen 3 Prius before this, and neither of them behaved like this under similar conditions. The only time I ever saw the engine spin up during braking on those was when the battery was full and it needed to dump excess charge when braking down a steep hill, which makes sense. This doesn’t seem to be that situation.

I'm not noticing any fuel economy hit, averaging 55-60 during my daily 100-mile commute. I've doubled checked the HV battery filter and fan to ensure they were clean. Dr. Prius app shows no strange voltage differential of the cells, and battery temps are good.

Is this just a gen 4 quirk and I'm overthinking this? Thanks!