They've made opt-in Replace-By-Fee (RBF) the default in Electrum version 4.4.0. If you want to use the old version without this feature by default, you can install version 4.3.0 using the following steps:
git clone
https://github.com/spesmilo/electrum.gitcd electrum/
git checkout 4.3.0
pip3 install -r contrib/deterministic-build/requirements.txt
pip3 install .
You can use old version of Electrum but every transaction will automatically have RBF enabled on the node.
Only option is to change node in Electrum to your own full-RBF-disabled node.
And
mine in secret this transaction.
However, once the transaction is broadcasted using any (API) method, it is at risk of being replaced.
Even if you share it privately with a third-party miner, that miner could still replace it..
So friend, the entire test was done with an old version of electrum, where it was possible to deactivate the RBF option, as you can confirm in the transaction itself that it was deactivated, perhaps electrum removed this option from the wallet in the most recent updates because miners did not they were respecting it, in other words, it doesn't make sense to have the tool and it not work as it should.