Personally, I had not heard so my opinion comes from the 3rd paragraph of the story:
The FBI's reliance on the anti-Trump dossier is questionable because while the judge was reportedly told the author had political motivations, the FBI allegedly did not disclose who funded it:
If this is true, then the judge should have, at the very least, put the request on hold until unbiased evidence was presented. The 1st warrant request (presented to a different judge) was denied. Whatever the denial was based upon should have given the second judge a basis for framing the follow-on request.
In principle, the fact that source is politically biased doesn't preclude it being factual. The FBI protocol is to verify every statement presented to the judge. It is the FBI's bias that has been hidden from the judge, as well as the FBI taking advantage of the judge making a false assumption that the FBI follows its own rules.