It’s very rare indeed to win something big out of 6 free spins on PP slot provider because they started to get sucks on rewarding players. X63 with only 6 spin is a very sweet deal. I believe you will have a hard time hitting that multiplier if you choose Bgaming Merge Up since it's a high hit ratio game yet very low payout. Most likely you will get small win each spin.
I have this 6 spin too but I use merge up since PP is unavailable to my country without VPN while I done have VPN right now to bypass this restriction.
Can you share the winning spin vids? It's available on your menu tab under the hamburger sign or 3 lines if IIRC.