rocket science it is not. There's a possibility that the tension difference between 9s and 10s is that drastic, but i didn't find it to be so going from 11s to 8s, so ymmv.
as long as you do not over-turn and over-torque, it's hard to mess things up on a telecaster.
check the saddle...
unless there is magic happening, one has to think about this in terms of how the various physical, acoustic, and electromagnetics systems might interact.
my guess is that the interaction between acoustic resonance and electromagnetic inductance and signal transmission is counterintutive: i.e...
to & from Tucson from Fort Worth. My mom driving. 1 return trip that thing was pegged to 120 all the way to Abilene cuz we had to get to the airport (the one before DFW opened) to pick up my sister getting back from Europe. From then on in she dropped down to a respectable 85.