RBF activation and deactivation option is available in Bitcoin Core.
If I transfer the private key to Bitcoin Core and disable the RBF option from there, will there be a definitive solution if I start the transfer process from there?
There is no guarantee for such transaction that private key will be leaked in less than a minute but you have to disable RBF, set highest fee and pray to God that the tx will be confirmed before any attack.
You haven't found the private key yet, so what are you worried about !?
This thread broke my motivation to keep searching. I'm thinking of pausing the search if there isn't any definitive solution.