POV: If your argument against the SSPX defending the deposit of Faith is "Deposit of Faith According to who?" You don't even have generic Christian Never mind Catholic faith
Look, i get obedience and i get people disliking or having a different take on the SSPX sure. and if you think SSPX isn't doing this to uphold the deposit of faith ok....show me how it dosent uphold it point by point...show me how Vatican II is just horribly misunderstood.
That Said
What was taught before Vatican II is well documented
Converts find out what the Church teaches without daily updates from the Vatican every hour and indeed, doing so is how they know they should even listen to the Vatican at all.
Didache, Church fathers, all the other councils which litterally are all on public record and easily accessed.
If you are using "deposit of fiath according to who" you either
a) don't know/believe in the deposit of faith and reject the known truth
b) are too lazy to find out
And SSPX has Bishops and priests who have studied this for 7 years do your homework or else don't discuss, gaslighting and being a karen isn't apologetics