Yes there seems to be a direct relationship between longer efforts and this problem. Yes this speeding up is our algorithm in process when things get behind.
And yes, I think notifications and extra background processes are a likely cause of triggering it but since it usually seems to happen more towards the end it would seem it should be performance related (our theory is that it it’s because a lot more data points are plotted), but your phone is so fast it’s an interesting case. I have an 11pro and have never seen this but I have zero notifications and very little running in the background. I also rarely do long workouts but I have and my team has run tests for 2 hours many times and never see anything. We even put the app in the background for these tests and if it does slow down it just speeds back up to fix things.
Ok let me work with my developer and this debug option might help at least to test our potential fixes.