iTunes&Helper to iPhone repeated error logging

I have tried to switch off automatic and wifi connections/remotes etc wherever I have seen any options between my MBP (10.11) and iPhone SE (12.2).

However I see every minute or 2 in my error log (500 instances each message per day approx if I ignore number changes such as pid, mux, pid):

Apr 24 19:12:52 ⋮ iTunes[21504]: Entered:_AMMuxedDeviceDisconnected, mux-device:782

Apr 24 19:12:52 ⋮ iTunesHelper[1240]: Entered:_AMMuxedDeviceDisconnected, mux-device:782

Apr 24 19:12:52 ⋮ iTunes[21504]: Entered:__thr_AMMuxedDeviceDisconnected, mux-device:782

Apr 24 19:12:52 ⋮ iTunesHelper[1240]: Entered:__thr_AMMuxedDeviceDisconnected, mux-device:782

Apr 24 19:12:52 ⋮ iTunesHelper[1240]: tid:6443 - Mux ID not found in mapping dictionary

Apr 24 19:12:52 ⋮ iTunesHelper[1240]: tid:6443 - Can't handle disconnect with invalid ecid

Apr 24 19:12:52 ⋮ iTunes[21504]: tid:2408f - Mux ID not found in mapping dictionary

Apr 24 19:12:52 ⋮ iTunes[21504]: tid:2408f - Can't handle disconnect with invalid ecid

of course there is a matching connect somewhere too:

Apr 24 19:15:01 ⋮ com.apple.usbmuxd[90]: notice device connected: 783-fe80::893:fe76:1b73:9f4d:0

Others have seen this too on later OS versions (e.g. https://discussions.apple.com/thread/250218166)

It stops if I remove the iPhone from the network (both are attached to the same wifi router).

I also note that airdrop will not work between this pair of devices, although the attempt to open airdrop window in Finder on Mac will start logging lots of BTLE blue tooth based mux connect and disconnects in a rather similar way. I guess I could set up and catch the log for that but it's been a long day already!

This behaviour remains across reboots. I reboot rarely, 6-8 per year, but did in the last few days.