Since I haven't been involved with Bitcoin for a long time, I have no idea about the current technical circumstances, but I came across an article reporting that Arkham Intelligence has developed algorithms and patterns to completely deanonymize transactions, even Coinjoins.
I wouldn't trust what Arkham Intelligence say without proof. They have fair amount of controversy and their platform sometimes contain inaccurate/wrong data.
I agree, and we cannot be certain of anything a big entity does - no matter what it is, it's prone to mistakes, as it was said, there are cases where some transactions are going to be tagged anyway.