For all validators that have lost their mnemonic (and are still stuck on 0x00 withdrawal credentials), I’ve put together the following initiatieve: deprecatebls.com
I propose a recovery mechanism here by proving ownership of your validator through signing a simple message with your validator key (keystore JSON).
More info is also on this topic:
Feel free to reach out to me on the ETHStaker Discord. In the #key-management channel. I’m w000t.eth there