Here are my pet peeves:
1. Replaceability - let's just hope that Sony didn't pull a RED with storage and default SSD has no proprietary code on the chip. In RED mini mag storage, in the enclosure you have regular SSD, but with code of their own making, which makes it impossible to replace the storage outside of buying new mini mag. If that may be the case here ("protection of customers from low quality replacements"), then it may be a bad experience for users.
2. Whole trim, over provisioning, and MTBF - it's an issue as soon as you start recording video. Which in this case a lot will do. This may wear out SSD rather quickly. As an example, 825GB SSD with 600TBW, after first game installed leaves you with ~400GB and 300TBW for free part. Another game will shave free storage to ~100GB and ~75TBW. Assumed 50MBps capture (avg of what smartphones record at 4K) results in 22GB per hour. This means up to 5h of recording will fit at once, and such single session will shave the TBW by said 100GB (about 1/1000th of original value). It's 3 years for avid gamer to averaged failure time.
3. Performance drop at near-full capacity. Including read speeds(which are crucial now for PS5). From my limited tests and literal few benchmark I could find, you can expect about or even less than 20% of original speed at near-full capacity (TLC drives). Hope this will be enough to load assets quickly enough for uninterrupted gameplay.