I wonder somebody else has recognized a similar behavior?

Mailcow is up to date and standard outside of traffic as reverse proxy. It runs since months without any trouble.
Just four accounts and 10 devices. 7 of them are iPhones & iPads. All configured to use ActiveSync.

Two of the iPhones were updated two IOS 16 for more than a week now. After that, I recognized very quick battery draining for both. Battery statistics under settings says it’s cause by mail usage up to 90%/hour.

I review the mailcow logs regular. I recognize that the Dovecot and SoGo logs are “flooded” from these two IOS 16 devices every second:
Dovecot:
27.09.2022, 18:45:14 info imap(USER1@mydomain.net)<162101><HsdSXqvptXXXXXXX>: Disconnected: Logged out in=224 out=5305 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0 27.09.2022, 18:45:14 info imap-login: Login: user=<USER1@mydomain.net>, method=PLAIN, rip=172.22.1.248, lip=172.22.1.250, mpid=162101 27.09.2022, 18:45:14 info imap(USER1@mydomain.net)<162099><Y3hJXqvpsXXXXXXX>: Disconnected: Logged out in=224 out=5305 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0 27.09.2022, 18:45:14 info imap-login: Login: user=<USER1@mydomain.net>, method=PLAIN, rip=172.22.1.248, lip=172.22.1.250, mpid=162099 27.09.2022, 18:45:13 info imap(USER1@mydomain.net)<162097><6pA/XqvprXXXXXXX>: Disconnected: Logged out in=224 out=5305 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0 27.09.2022, 18:45:13 info imap-login: Login: user=<USER1@mydomain.net>, method=PLAIN, rip=172.22.1.248, lip=172.22.1.250, mpid=162097 27.09.2022, 18:45:12 info imap(USER1@mydomain.net)<162095><XBM2XqvpqXXXXXXX>: Disconnected: Logged out in=224 out=5305 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0 27.09.2022, 18:45:12 info imap-login: Login: user=<USER1@mydomain.net>, method=PLAIN, rip=172.22.1.248, lip=172.22.1.250, mpid=162095 27.09.2022, 18:45:12 info imap(USER1@mydomain.net)<162093><ys8tXqvpUKWsFgH4>: Disconnected: Logged out in=224 out=5305 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0 27.09.2022, 18:45:12 info imap-login: Login: user=<USER1@mydomain.net>, method=PLAIN, rip=172.22.1.248, lip=172.22.1.250, mpid=162093

SoGo:
27.09.2022, 18:45:14 notice [62]: 172.20.0.1, 172.20.0.1 "POST /SOGo/Microsoft-Server-ActiveSync?User=USER1@mydomain.net&DeviceId=XXXXXXXXXXXXXXXXXXXXXXX&DeviceType=iPhone&Cmd=Sync HTTP/1.0" 200 0/68 0.148 - - 0 - 13 27.09.2022, 18:45:14 notice [62]: 172.20.0.1, 172.20.0.1 "POST /SOGo/Microsoft-Server-ActiveSync?User=USER1@mydomain.net&DeviceId=XXXXXXXXXXXXXXXXXXXXXXX&DeviceType=iPhone&Cmd=Sync HTTP/1.0" 200 0/68 0.147 - - 0 - 13 27.09.2022, 18:45:13 notice [62]: 172.20.0.1, 172.20.0.1 "POST /SOGo/Microsoft-Server-ActiveSync?User=USER1@mydomain.net&DeviceId=XXXXXXXXXXXXXXXXXXXXXXX&DeviceType=iPhone&Cmd=Sync HTTP/1.0" 200 0/68 0.159 - - 0 - 13 27.09.2022, 18:45:13 notice [51]: <0x0x56498ba97d70[SOGoActiveSyncDispatcher]> Sleeping 45 seconds while detecting changes for user jes@mydomain.net in Ping... 27.09.2022, 18:45:12 notice [62]: 172.20.0.1, 172.20.0.1 "POST /SOGo/Microsoft-Server-ActiveSync?User=USER1@mydomain.net&DeviceId=XXXXXXXXXXXXXXXXXXXXXXX&DeviceType=iPhone&Cmd=Sync HTTP/1.0" 200 0/68 0.159 - - 0 - 13 27.09.2022, 18:45:12 notice [62]: 172.20.0.1, 172.20.0.1 "POST /SOGo/Microsoft-Server-ActiveSync?User=USER1@mydomain.net&DeviceId=XXXXXXXXXXXXXXXXXXXXXXX&DeviceType=iPhone&Cmd=Sync HTTP/1.0" 200 0/68 0.155 - - 0 - 13

These are the logs for one device!
Rebooting the iPhone or restart SoGo, it stops for a few minutes up to eight hours before it starts again to produce these entries every second.
I tried to delete the account on one phone and recreate it > no success
For testing I have changed one phone to Imap & Card-/Caldav. This solves the problem for this device.