As I said, the mined fee has a lower, not higher fee. So this is very strange to me.
This is not strange.
RBF is, in simple terms, a second transaction that you will send with a higher fee to get a faster confirmation.
His first transactions with lower fee was not confirmed, so he sent a RBF.
But both of those transactions were confirmed at the same height, in different chains.
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The only thing that does not add up is, as I said in my comment above the LOWER FEES transaction was confirmed, AND this transaction appeared AFTER the one with higher fees.
So definitely not a standard RBF transaction. Like the sender “colluded” with the miner to have this second lower transaction in the block.