Matt Sorum was playing with The Cult, and he was recruited by Slash of Guns and Roses, so he played with Guns and Roses, but he has since returned to The Cult. What is wrong with the sentence?

What is wrong with the given sentence above is the overuse of conjunctions to make it into one sentence. This common sentence error is called a run-on sentence. The thought of the whole sentence becomes chaotic because of too many ideas that are forced to be put into one. Hope this answers your question.