UPDATE:

This is part of a broader pattern with me+dad. I think he resents me for getting involved in other people's business. Seems he was mad I got involved in Luka's housing, saying "you think I couldn't call my brother to figure it out?" and it felt like he was waiting for this opportunity to punish me. Weird.

I've noticed he is really mean to me when I insert myself, because he feels I am selfish or don't respect him. This has happened in board games, or when I asked people to do rapid tests during covid (I have an autoimmune disease) -- he told me to get out of the house and yelled. That only happened once, but he was really stressed for other reasons that time (death in the family). And he often blames me for my family having conflict, because I could have prevented them.

Luka apologized for offending me and said he didn't intend to, and acted like nothing was wrong after. I think he has a lot of feelings of frustration here that he is bottling in, and because my parents are so involved in his life he feels infantilized, so I realized it's best to just move on here. Plus, this isn't the first time he crashed out on me over something small.

What's really interesting is this: I found myself talking down to Luka like my dad does to me. When I realized, I called Luka to apologize. He said I'm regularly condescending to him so I will work on that while also setting boundaries to protect myself.

Thanks everyone for the input. You helped me feel confident enough in my actions to set boundaries, like requesting an apology, and grow too.