My great uncle slapped my ass every single time I would go to visit him

So I wouldn't consider this assault maybe just harrassment. But my great uncle on my dads side slapped and grabbed my ass literally all of the time. Every time I went to see him without fail😭 one time he even had a ruler in his hand and slapped my ass with that while I was going up the stairs. I felt really grossed out but I just brushed it off I've been through worse (it's still weird). I don't know if this is just family traditions or if it could be a violation. When I talked to my mom about it, she said "oh it's just a football pat." But the thing is It's not a football pat, it's a slap with force in it😭. Like I even remember this time I purposely tried not to greet him and tried to get away from him, and he chased me down , gave me a hug and you guessed it, slapped my ass. like the mf just had to cop a feel. I don't understand it. Is this normal behavior for some ppl?

My mom actually found out that this same great uncle was accused by another family member of rape. So then my dad's side kind of excluded that woman who accused my great uncle. And my dad even still goes to visit my great uncle despite these accusations. My mom and my dad still get into big blowouts about my dad's side. There was a lot of COCSA and just CSA in general going on in that house (my great uncle) but that's a whole different conversation. But yeah is this assault or harassment or am I just overreacting or something? It doesn't bother me that much but I do find it weird and gross.