Thanks for the pointer, we haven't checked out OPAL yet. It seems to be the most popular standard when it comes to "Self Encrypting Drives" (SED).
Looking into it shortly, I've found a paper from 2019 from Meijer et al. ([1]) finding several flaws with OPAL-compliant drives. They further find that BitLocker entirely depends on SSD-based encryption if the hardware advertises it. This finding's nature is very similar to ours in that BitLocker's Disk Encryption is insecure/unreliable in particular hardware configurations.