Apple doesn't support downgrading.
In order to check if it is a temporary glitch, try a "forced" restart of your XS using these instructions: Put it on charge for at least half an hour, then, keeping it plugged in, use these gestures:
In rapid sequence, press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the side (power) button. Only when the Apple logo appears (it might take 10-20 seconds), release that button (ignore all other screens that might appear, the one with the "slider" to turn the device off included).
If the issue persists, if you can, check your battery status in Settings>Battery>Battery Health & Charging>Maximum capacity. If it is close to 83-80%, have it replaced as soon as possible, since it might have unpredictable behavior.
If the issue still persists, it could be a hardware (digitizer? battery? other internal component?) failure, and I suggest that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . After checking it out, they'll give you all the available options.
Regards
Giulio
(*) You can do it: