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From what you described is two thing;
Stem bolt not torqued enough causing it to move upward.
Steerer expander move when you tried to preload the headset and torque stem.
Its likely the latter, there may be a play where it feel like the brake pads is moving, turn the wheel 90 degree and rock bike back and forth with brake on while having your hand on the junction between headtube and headset, you either don’t feel any movement, or a tiny bit.
Tiny bit = not preloaded enough.
edscoble
It’s trash.
This is very common in even big names brand, when they still use compression ring made out of metal, which mean if the headset isn’t preloaded correctly, it can cause a wear groove.
Only recently manufacturer started to use plastic compression ring but ultimately it’s down to how the bike is set up; if you felt a slight play, don’t wait around, fix it.
Example of a fork we wrote off with confirmation from said manufacturer.