I'm probably blinkered but Kompany's tackle on Salah was much worse.
Kompany was running at full speed and jumped into a tackle in such a way he was certain to hit Salah. The only defence of the challenge was that he won the ball but that was only because he spread his legs so wide in the lunge.
Boly was arguably a red but the tackle was more like Van Dijk's against Napoli that Kompany's. He won the ball cleanly first but the follow through was raised enough to arguably merit the card.
I thought at the time with Kompany that it was only because the ref was somewhat blindsided to how high Kompany's second leg was that he only showed a yellow. Pawson seemed to get some indication from his assistant before showing the red.