-snip-
What you are saying is NOT what I have experienced.
-snip-But now, it has changed. It's no longer letting me increase miner fees as I wish when adding new transactions to the batch. Whatever change was made, at the wallet level, or at the Mempool level, it sucks. Because it's forcing me to pay more in fees.
Hmm it shouldn't be possible outside of that example scenario, it wouldn't comply to RBF standards otherwise.
Without any drastic difference in the original and replacement transactions' sizes, the average increase should be closer to 1sat/vB than 0.2sat/vB.
It would be best if you can provide actual examples of those past transactions and hopefully, mempool.space still logged its RBF history.