I can't find other examples, I thought they exist.
They do not.
Every block must have exactly one coinbase transaction, and that coinbase transaction must be the first transaction in the block. The coinbase transaction may collect the block subsidy and the block fees, or any portion thereof, but it doesn't have to. The coinbase transaction must also contain the block height as the first entry in its scriptsig (4 bytes) with a further 96 bytes of arbitrary data, which is how pools tag blocks as being found by them.
Blockchair makes it look like an OP_RETURN transaction.
It's supposed to be, but it isn't, because the miner clearly messed up. If you pull the hex script from that output, you'll get the following:
52534b424c4f434b3addbf517adf8ffd4bca7751505b39c9013a0d1fd479fc4e901b39dd57b347c624
The start of that - 52534b424c4f434b - decodes to
RSKBLOCK. If you look at any other recent block which has an
RSKBLOCK OP_RETURN output, you'll see the same string in its coinbase transaction. However, in this case, the miner has neglected to include the necessary OP_RETURN bytes at the start of the script (0x6a29).
