[but LHC was launched first time 2008 and people have experience mandela effects before LCH so arent there conflict on all this]

You aren't thinking outside the box bro. The act of particle acceleration has been around for quite some time. Particle accelerator - Wikipedia

I don't feel this theory would work with Linear accelerators, However, those have been around since the 1920's.

Here is a ring-shaped accelerator from 1935 Germany, Betatron - Wikipedia I feel the theory came before the experimentation. I think CERN had already fully understood the principle and nature of the experimentations they wanted to do, and didn't fully realize this until the LHC. They must have needed a particle accelerator that large for a reason. As for the time displacement itself, I admit, It's there. But. Consider this, Two bubbles, Two realities collide into one by ripping space-time apart in the ring. space (TIME) The effects of this interaction, at least in my opinion, Would affect a multitude of different time periods. Not just time local to the accelerator itself. But, You do bring up an interesting point about the timing. I do feel the Mandela effect was created by CERN, But So many people never consider this as a phenomenon in Time itself bro.