I have had problems with a seroma, I've had to see my surgeon several times about it but it's not too bad for me, it'll eventually be sorted and it isn't too problematic in the meantime. I've had this seroma keep forming despite compression somehow. If it persists beyond new years my surgeon will consider reopening a bit on that side and putting a drain in again, but for now we've been doing repeated draining and compression. It's almost gone at this point, and I haven't personally seen a case of a seroma as long as I've had this, but I haven't seen much about seromas in the first place. It's gotten to such a small size that it's a minor aesthetic problem, but it doesn't cause any problems or look too strange, and still shrinking slowly but surely.
I haven't heard much from other trans guys about seromas, but from googling it sounds like it isn't unusual for procedures that include liposuction. It's pretty minor as far as complications go.