https://bitcoincore.org/en/doc/0.20.0/rpc/wallet/listsinceblock/
"to" : "str" (string) If a comment to is associated with the transaction.
I've read that extremely short "description" hundreds of times by now, having no idea what they mean.
There's no riddle here. The to field is a string that contains the comment associated with the transaction contained within the wallet, if there is one. The output of the help command is generally meant to be one line explanations rather than an actual manual, there's various commentary around that gives some more context.
It's just intended to be a human readable note intended to contain information about who the transaction was sent to. It's entirely optional and has no effect on the transaction itself.
