iPhone brightness control not working

The brightness bar both in control center and display & brightness is not behaving correctly on my iphone 11 running iOS 15.5. When scaling the brightness up from the lowest to highest setting once I hit about 50% the brightness stops increasing and is capped at the 50% brightness level even though the manual control bar is at 100%. I have True Tone off and auto-brightness off. When restarting my iPhone, the screen will briefly be back at a true full brightness before dimming itself in what appears to be 2 ~25% abrupt increments.