OK that isn’t the issue I was expecting! Have you moved the TV or put a MASSIVE magnet near it? because that is a magnetic issue that the tube usually has a degaussing wire to compensate and correct at power up.
when you turn it on do you hear like a ‘dongggg’ noise? have you tried unplugging it for a while and plugging back in (it might trigger the degauss, or set your stand to go from different on off positions as there is a degauss correction angle in the service menu of these TVs which I’m not 100% how it functions. either way it seems the degauss hasn’t worked. you can get external coils for professional use but that isn’t necessarily the answer – I wonder if a cap has blown in the degauss circuit and its now not working.