Unknown Address Format Parsing Bitcoin Addresses from Blockchair Data
Having investigated this following @MCCCS answer, the following is information about the addresses provided by Blockhair support:

In fact, there are no addresses on the Bitcoin blockchain. There are
only scripts, some of them are standard and can be converted to a
Bitcoin address, some of them can’t — like nulldata (OP_RETURN)
outputs, nonstandard, and bare multisig. We use the d- prefix for
nulldata, m- for bare multisig, and s- for everything else.
This is briefly mentioned in this API documentation section:
https://blockchair.com/api/docs#link_300

Therefore, these addresses (for want of a better word) are valid transactions on the Bitcoin blockchain.
The prefixes used are:

d- nulldata
m- bare multisig
s- everything else

In conclusion, the data is valid but the outputs are not addresses in the normal sense of the word.
A link to the issue I raised on the Blockchair GitHub is here.