Myles does this too. It started with him around 9 months (maybe a little younger). When he was really tired and/or angry he’d slap my face. Even though I found it somewhat amusing
I would always firmly tell him “don’t hit.” If he tried to hit me again I’d hold his hands and say, “don’t hit” and if he kept doing it I’d put him down and then he’d cry to be picked back up and he usually would not hit me again. So, the hitting stopped within a few weeks, but lately he’s been doing it again. I’m being firm with him and I’m sure it will stop soon.