According to ESPN :
"In the closing seconds, Browns defensive end Myles Garrett tackled Steelers quarterback Mason Rudolph. They started fighting on the ground, and grabbing each other's helmets.
Garrett actually yanked Rudolph's helmet off, and then used it as a weapon . . .swinging it at Rudolph and BASHING HIM IN THE HEAD.
Several Steelers players including center Maurkice Pouncey tackled Garrett, throwing punches and kicking him in the head.
The Browns came in with their own aggression, and Browns defensive tackle Larry Ogunjobi shoved Rudolph to the ground, AFTER he was hit with his own helmet. It was a cheap shot.
Garrett, Pouncey, and Ogunjobi were ejected. Garrett and Pouncey will surely be suspended . . . but it's unclear how long. There's some talk that Garrett could be out for the rest of the SEASON.
Cleveland quarterback Baker Mayfield called Garrett's helmet hit "inexcusable." And Browns coach Freddie Kitchens said that he was embarrassed and that Garrett is embarrassed. Garrett himself called it "foolish [and] out of character."
It's worth mentioning that Rudolph instigated the helmet grabbing by trying to pull Garrett's off FIRST. Not that that excuses Garrett's actions.
Earlier in the game, Browns safety Damarious Randall was ejected after a brutal helmet-to-helmet hit on Steelers receiver Diontae Johnson, which left him bleeding from the ear.
Not that anyone seemed interested in the actual game after that , but the Browns won 21-7.
Here is another angle -