Has anyone tried reverting back from macOS 26.2 to macOS 15.6.1, using this method?

Hi all, please let me know if anyone has used this method, my MBA 8GB Memory and 256GB SSD is fine running on 26.2 but I feel like it was faster before updating OS to 26.2.
Similarly it also has option for iPhone so I am thinking to revert back to 18.6.2 for my iPhone 13 Pro Max 128GB.

If its safe and people have had any success then I'll first try on my iPhone and then macOS

Video: https://youtu.be/B84-MMrOWbM?si=qAmwI3NB3Z5F2FEQ

PS: I have asked this question in r/mac but posted here to hear back from more people since I haven't had any answer in other subs.