mixed player pack and found a tradeable base card

I opened a mixed player pack and found a tradeable base card Nico Williams (currently 170k on the market), who is also available with his special card in the Pillars event (currently 950k on the market), which ends in a few hours. I wanted to know if it's normal to find base players even if they're available in events, or if it's a bug.

[Edit, EN only here please - CM]