The Mind Flayers have a legend about the "Adversary" - an unusual representative of the race who retained his personality before the transformation and plays his own game. Perhaps Lolth and Shar are also involved.
Most likely he is a strong psionic and a wizard, and in the Moon Towers will appear to us in the form of the Goddess Absolute, most likely in the same form in which he comes to us in dreams. This will be the illusion that we already saw in the first act. Thanks to his illusion, he managed to plant a tadpole on the goblin leaders without them noticing it.
Something went wrong with us, we have a tadpole and his power, but there is no direct control of the Absolute over us, and therefore we can reveal his deception. This is the main reason why he wants to destroy us, even if we are helping the goblins.
This is my guess
Thanks to Larian for Baldurs Gate 3 and the reaction to player feedback
