Is there anyway to prevent this? No matter how good I cut the tag end after. A few casts it seems to fray. It’s 50lb power pro on my frog rod. Does the frayed tag end have any negative impact on the knot? 

Not that I've noticed - long as the fray stays out of the knot itself. It's just something that happens with multi-strand line - whether that's braid for fishing or rope for tying up the boat - a cut end will fray.

CAREFULLY burn it with a cigarette lighter. Totally eliminates slippage, too

 

https://www.tacklewarehouse.com/Berkley_Hot_Line_Cutter/descpage-BHLC.html
 

it also works to mushroom the tag end of FC when tying the FG knot

I just leave it be

No , your good to go .