About a month later: 18.1 did not bring relief but the system is *slightly* less laggy. Persisting problems:
CAMERA continues to hang up and is the most frequent cause for initiating restart. The camera might appear to snap a shot but none is saved. (40GB storage space on the phone with 2T iCloud backup & storage optimization on)
Inability to MULTITASK: e.g. listening to music (an album saved on the phone so theoretically required less resources) and turning on the camera instantly freezes the system.
Issues with CALLS: regular but mostly WhatsApp - if receiving a call after having used other apps, like reading mags, chances are the call won’t come in smoothly ( inability to hear or be heard).
ISSUES I AM SEEING LESS OFF: Fewer instances of sticky keys, seem to be able to type normally. Dictation ok.