Seems like they are real.
They're not 
It's something Blockchair made up:Q&A
Can you please clarify, what is the type of these d- and s- addresses?
This is how Blockchair.com shows OP_RETURN. From the main page the search field doesn't show them, but you can replace a Bitcoin address in the URL to find them: https://blockchair.com/bitcoin/address/d-d0d953f2e7043342540a1407243e49fe.WOW!
That's wild!
Looks like D is not the same as d and S is not the same as s.
Sorry, my answer above is correct, but not accurate to your point.