This is the final replacement that got finally confirmed:
https://mempool.space/tx/b5fe2c4891cba365c0863b8645a7e7a4c7e7191804508f4549f870be6012102fI've counted more than 30 replacements of the original tx that were done within 40 seconds intervals on average. This kind of txs have only one input and only one output. This is why they are cheap since their size is ~109 vB. There are many of them and increase in their number coincides with tx fee spikes.
Looks like this is a job of a mining cartel as it tricks Bitcoin Core's fee estimation algorithm.
It doesn't. RBF transactions are always replaced by wallets who uses mempool size as the calculation algorithm. You can't inflate your mempool count this way because transactions spending the same inputs are getting kicked when another one comes in. Bitcoin Core only considers the moving average of confirmed transactions, which would mean that the replaced transactions has no impact on fee estimates.
Hence to effectively trick Bitcoin Core's fee estimation, it would be better to intentionally include only high paying transactions. This looks like someone trying to use RBF to ensure that their transaction has the best chances of getting confirmed within a short timeframe.