It is unknown whether the faculties of the SSPX to hear confessions was ever fully revoked. The Vatican has never investigated and declared any particular confessions null.
Thee SSPX have had no ministry in the church for many years, and thus no right to hear confessions. However, there are so many contingencies in Canon Law in favor of the faithful that it would be irresponsible gossip to for an uninvolved layperson to say SSPX confessions were invalid, especially in all circumstances. The most one could do is warn another of the ambiguity.
That said, the Pope explicitly granted faculties to the SSPX, eliminating any ambiguity. These faculties have not expired, nor been revoked.
The Pope eliminated this ambiguity for the benefit of the faithful cared for by the SSPX.
In granting these faculties, he made absolutely no statement about whether prior confessions were invalid. This was not investigated nor is it possible to investigate. Suspended priests, even defrocked priests, are bound by the seal of the confessional. Any sin confessed can never be discussed, so any contingencies in Canon Law that might have granted faculties for a valid confession cannot be known by uninvolved parties.