A friend of mine has the same problem (Xperia 10 iii, build 4.4.0.72, device adaption 1.0.0.176) while my device does not suffer from this (same device, build and device adaption)
Both first flashed with Android 11 before installing SFOS.
What Android versions did your device have prior to installing SFOS?
EDIT:
My device was installed with 4.4.0.64, while my friends’ device was installed with 4.4.0.72 which shouldn’t be an issue.
EDIT 2:
My friends’ phone was originally flashed with Android 11 → SFOS 4.4.0.64 (which was buggy) → Reflashed to 4.40.72. The charging problem occurred some time after.
Today we flashed it back to Android 11 (using emma flash tool) and then flashed to SFOS 4.4.0.72 and charging works again.
EDIT 3:
After a little week the problem reoccurred on my friends’ Xperia 10 iii 
EDIT 4:
@DrYak What firmware version did you install SFOS on and what SFOS version did you install perior to upgrading?
I’m thinking that this is some strange kind of sw issue where maybe a new SFOS version as base is the root cause and I’m thinking of trying to use the latest Android 11 firmware ( 62.0.A.3.109) with the older SFOS 4.4.0.64 just because this works on my own phone (upgraded in settings afterwards) or maybe try Android 12 (62.1*) and SFOS 4.4.0.72.
EDIT 5: In the changelog from 4.4.0.64 to 4.4.0.68 this is listed under our device adaption “Do not log battery status to kernel log”. I just can’t figure out why this would impact my friends device flashed with 4.4.0.72 while mine (4.4.0.64 and upgraded to .68 → .72) is unaffected.
UPDATE: Possible cause found: Android began complaining about dust/liquid after a week after reflashing. Cleaning the port with a tooth pick and cotton swab made Android stop complaining. My friend will reflash Sailfish in about a week if the issue does not come back.
UPDATE 2: TLDR: Caurse confirmed. Dusty charging port needed cleaning:
Yesterday I had the same issue as my friend. Also with an Xperia 10 iii running 4.4.0.72 showing that et charges without actually charging. Rebooting didn’t help, but powering it off and cleaning the USB-C-port with a couple of cotton swabs that turned dirty helped as it began to charge after booting the device again.
I might submit a feature request for warning the issue depending on charging status.