Who knows for sure if there is paper Bitcoin being traded or if those doing it will blow up. But Coinbase & MSTR could easily provide on chain verification, that is the ethos after all. If Kraken can provide proof of reserves, so can Coinbase. That they don't says alot. Their ridiculous cbBTC is also probably part of a way to count non Bitcoin assets as Bitcoin.

Certainly going to be interesting next year who will blow up. All bets are open with many Ftx-esque candidates.