Inspired by this post by @renaissancemeetsworld, thanks for the emotional devastation!!!
Mike does what makes him happy without shame, with his friends that he loves. Both times he plays D&D, Will is there.
Losing toys is a punishment for not behaving correctly. Thus a conundrum: behave correctly according to parents or lose toys? Or try to behave correctly and also act like you're not interested in toys because it's clear now that your parents look down on you for playing with them still?
Mike tries to behave correctly, dating a girl. He still tries to be silly, but he gets more messaging that who he is isn't right, it's wrong and embarrassing.
And so he shoves it down. Both sides. He acts more straight and acts like he thinks D&D is childish.
Around El he reverts to shame about liking toys and that is linked to his shame about his sexuality. The story has intertwined those two ideas so closely. Toys and boys. Mike likes both, but he's being told he shouldn't like either.
Mike is "being more rebellious," doing what makes him happy even if his parents disapprove. He's still playing with toys, playing D&D, and it's the happiest we've seen him in ages. He's still working on the fact that what his parents think is appropriate for his behavior isn't always what's best for him though, and he doesn't get that yet. He is still with a person that he can't play D&D or sing with. He's still missing part of this puzzle of growing up and figuring out for himself who he is and what he wants and if he's going to let other's opinions get in the way of that.
S5: To complete this arc, Mike will figure out that life doesn't have to be a lose-lose situation. He can win. He can be himself, do things that make him happy and be with the person that makes him happy. He can be with Will and play D&D and Nintendo for the rest of his life because that's what makes him happy. He can like toys and boys, and that's okay!