What brass make are you using ?

How many times has the brass been reloaded when it was shooting good ?

Did you change lot # of the bullet ?

Did you change lot # of the powder ?

Can you swap scopes to a known good scope to verify the current scope is not the problem ?

Those are just a few things to look into.

I had the same thing happen some years ago with a 308win load. Ended up being that I over-annealed the Lapua brass !