So I batched transactions in the past. And when I did, if the first transaction was at 1 sat/vB, I could just do 1.2 sat/vB for the second one, and I would save a considerable amount of money on fees.

But something has changed in the Electrum implementation of that.

Yesterday, I did some tests. I sent one tx at 1.2 sat/vB. And when I tried to send a second tx, I input 1.3 sat/vB. But the wallet batched the two transactions at 1.99 sat/vB. As you can see in the link below:
https://mempool.space/tx/044e97e73663dd351953b8c49d0a74ac8c35b38087d0aeb5b788ba91cd05d3ff?mode=details
But instead of batching the two txs into a single transactions at 1.3 sat/vB, it batched them at 1.99 sat/vB.

Than I tries adding some more sends into it at 0.1 sat/vB each. But each time, the total miner fees kept going up to 2.69, 3.34, and 3.95 sat/vB.
So in the end, I really don't save all that much in miner fees. Each transaction would have been at around 1 sat/vB each for around $0.20 USD if I were to send them separately. But batching 5 of them ended up costing $0.80 USD total. So I really didn't save much at all.

How can I increase miner fees with each added spend at around 0.1 or 0.2 sat/vB ? Is that no longer doable?