Actually, we DON'T KNOW THIS. That would require a determination from the FISC court.
We do know that various people in at least three layers, as cited by the IG report, SHOULD have acted on the warnings that the dossier had not been vetted.
Throwing about idle speculation on this forum does not improve the information content.
Given IG Horowitz's testimony that the entire basis of the FISA application was the Steele Dossier, how would the court approve the warrant if there was nothing at all in the application? I can't think of a situation where a FISA warrant would be approved if there was no supporting material at all. Can you?