That's not called blooming, but no big deal.

If the splotches are stationary and onbly in certain modes it is most likely decoding errors, and that is usually on the main board. If it was in all modes I would say it might be the panel or Tcon, but it isn't.

Slight possibility of it being bad caps, but very slight.

Try looking for settings that are channel or mode specific in the menu(s). Of you find them you might find the broghtness turned too low for one mode or sometning. Sometimes LCD panels "overtwist" which can do things like this. That is ALOT more noticable on an edgre lit display like a laptop PC. Regular backlit monitors are alot better about that now, unlike years before when they didn't have the viewing angle.

If it is overtwist, likely you will see a difference when you change your angle. I it looks significantly different from the left, right, above or below, just adjusting the brightness (pedestal) might fix you up. I do not mean in different places, I mean more or less pronounced.

Even if there is a minor fault, adjustments might make it watchable. Especially if it has a gamma control. I doubt it does, but if it does you can play with that.