The Faith is the condition for grace; the sacraments do not sanctify in union with error.
The SSPX is under a practical agreement. They accept Rome’s jurisdiction. They accept Vatican II “in light of Tradition.” They declared the New Mass legitimately promulgated in 2012—and never retracted it.
That’s apostasy in practice.
> “Even if they give us everything—we refuse if they don’t convert.”
— Archbishop Lefebvre
This isn’t a question of sacraments. It’s a question of truth. You cannot drink from a poisoned well and call it grace.
Yes, the SSPX has gone the wrong direction since after the death of +ABL, what else is new? Every one of the various trad groups out there are wrong-headed about at least one thing or another. That's the way it is in this crisis.
The SSPX has thus far ordained for the world valid priests, so the sacraments are certainly valid - your opening sentence is ambiguous at best, as regards those who go to the SSPX, it applies only to those who receive them unworthily.
They still have a lot more very good valid, orthodox priests than any other group out there, and they preach the Catholic faith. Use them whenever you can for what you need, but don't paint with a brush so broad as to condemn them all.