Apple Watch Series 8 Locking (and pausing workout) when running

My Series 8 keeps locking when I’m running which pauses my tracking but does not notify me. I’ve tried the water icon locking it so the buttons can’t be accidentally pushed, still happens. I’ve cleaned it, and it’s not too loose. Not sure how to fix this as I bought it for the workout tracking and don’t want to have to use another app on my phone.

[Re-Titled by Moderator]