IPHONE LAGING/ FREEZING!!
My iPhone 8 Plus started to lag and freeze my screen? Why and could it be a bug fix?
It is not a bug, but you can use this to deal with freezing, If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support
Create a current backup of the phone and the restore to backup. If that does not fix it, then restore the phone to factory and set it up as new, not using a backup and test.