[2021] Does Paladin Class have a bug?

I was playing a sealed game and an opponent level up [[Paladin Class]] to level 3 and attacked with one creature. It still got +1/+1. Similarly, in this example, he attacked with 2 creatures and got +2/+2. The card clearly states "every other attacking creature". Am I missing something or did I just lose a game to a bugged card?

Thanks for reading.