Interesting...
I'm not too familiar in Bitcoin Core's fee estimation algorithm but my initial guess is it's trying to trick the fee estimation by continuously broadcasting high fee replacement transactions with enough delay for the previous transaction to propagate.
Since it's a replacement, each relayed replacement is cheap since it'll only need to add a few satoshi on top of the transaction that it replaced.
But I'm not sure if the fee of the replaced transactions that a node relayed wont be removed from its "bucket" and if those will still be counted to its fee estimation after the last replacement is confirmed though.
If it is, that could be the purpose of those rbf spam.
Doesn't Bitcoin Core look at the amount of time transactions take to confirm with the historical statistics? If it only considers the fees of transactions which are eventually included into a block, then it would mean that any transactions which are replaced would not matter since it wouldn't be confirmed.
But if you make non-RBF transaction can’t it still be replaced if the server or node is full RBF opt in? Or is there way to know maybe a node isn’t full RBF so one can change server when looking to make a non-RBF transaction
Trying to replace a non-RBF transaction would only result in poor propagation. Nodes or miners who do not care about the RBF flag can still relay or confirm your transactions.