Body language - playing or aggression?

The cat on the left is Peachy, who we rescued from outside a few months ago. Introductions were really slow and he’s been doing well, but we watch playtime intently as he was diagnosed with FIV. Can someone please tell me what they think of this body language?

It seems to me that they were playing (both laying on sides) but then it got personal for both of them (hits became harder and Peachy’s tail fluffed up before he left).

Just want to make sure we don’t need to work with these two more to ensure safety. Thanks in advance! Oh, and sorry for the cuss word 😆