This is what you can do:

Not take any B6 at all for 3 months and get retested. Just take the folate and B12. Folate has no food restrictions like B12 has, so you can be more flexible with it.

Stop all vitamins a week before any testing as a rule.

B6 is really only a problem for PN if it gets really low. When deficient, that is when PN shows up. To get too much, you really have to have much higher amounts consumed daily, than what is in a typical B-complex.
This testing issue is very common on the net... you can Google it and find all sorts of people showing out of range test results.
B6 is stored in muscle for a short time, and not eliminated quickly. So it does hang around for several days.

So you can just forget about the B6 for a while, since it concerns you. See what happens with the MethylB12 and methylfolate.

B6 is not methylated...it is activated by adding a phosphate to pyridoxine. So the MTHFR is not an issue with its metabolism/activation.