Portuguese clubs knows how to scam buyers, Trincao isn't worth anything north of 20M as he still has same issues of speed and playing on slow motion without the rest of his game being elite to compensate for it. He is a squad depth in EPL at most.
The fact that they are likely selling him for more, speaks more about their ability to fool clubs into buying players, than our ability to sell.
It is the same as Nico Gonzalez, he is a 25M-30M player, whom they fooled City and sold him for 60M.
Good for them tbh, but it is nothing to look deeply into it and think we got screwed