about:config - ui.textScaleFactor - worked for me. And I wound up going with 112, not 100. My Windows display is at 125% (Recommended) and the "Make text bigger" slide scale I have set to 160. And it looks like everything is back to the way it was...
I think that's backwards. The Windows "Make Text Bigger" always affected Firefox, at least it did for me. But the 103 update blocked it (only on the FF browser). Unless another of my about:config tweeks changed it.
Go to about:config - ui.textScaleFactor - click number and enter 100, hit enter. See how it is. The lower the number the bigger everything gets. Higher numbers, smaller. So adjust accordingly.