iPhone 11 Pro Max disconnects from charger and randomly gives message Accessory may not be supported’ alert (apple charger)

THe Alert does not occur with every disconnect - may be 1 in 5.

I followed "If you see an ‘Accessory may not be supported’ alert

"https://support.apple.com/en-au/HT208277

The LIghtening connector socket in the phone is free of lint. Intermittently throughout the night it is makng the "ding" noise ( really annoying in Bed! )I bought a new certified tough Lightening cable - no change. The phone has done this since new.

Is this a bug?