You may “know” what the Catholic Church teaches, just as a divorced man may claim to know his ex-wife. Maybe not as well as you think ;-). I am just that being an ex- Catholic is sort of like being an ex-Protestant. It doesn’t mean that one has a thorough knowledge of the institution one has left behind. Indeed, we are probably disinclined to give full credit to to its teachings.
That’s working under the false assumption that if someone “really” knew what the Catholic church teaches, of course they’d understand it and be Catholic, that they couldn’t help themselves.
And that only those who choose to remain Catholic “really” understand Catholic doctrine.
That’s not true. Someone can be thoroughly knowledgeable about a subject and choose to reject it. Someone can be thoroughly knowledgeable about Catholic doctrine and choose to reject the parts of it that they don’t see lining up with Scripture.
The part that is the most ironic is that the Catholic church claims to be responsible for the Bible’s existence, and certainly appeals to it for authority to establish itself as supreme authority over everyone on the planet, and then dismisses anyone else’s positions when they try to use Scripture to support their position.
Sola scriptural is just fine to establish the papacy and transubstantiation, but not fine to contest it. How inconsistent of them.