I wanted to add my phone to the list of those having charging issues, starting yesterday (Monday). My last full charge was Friday night and I usually get two+ days on a full charge.
Yesterday morning with the battery down to 22%, I plugged in the phone using the charger that came with it and it charged up to 78% and then stopped and actually started to drain a little. I left it plugged in for a few hours and the screen would come on and off as it tried to charge but couldn't. I unplugged the charger and after a minute plugged it back it and would see the Turbo Power Connected message and it would appear to be charging. After a minute, it would stop charging and try again. If I leave it like this, the battery % would not increase. I checked the battery settings and saw the message "Plugged in, can't charge right now".
I tried this over and over all afternoon using my charger and my wife's charger (same model phone) and got the same result. Sometimes I would gain a couple of %, sometimes nothing. I tried the charger for my old Moto G3 phone and it seemed to charge a couple of % before cutting off, but then would stop charging as well. I tried this while the phone was on and while it was off. When off, the charging icon would show, then after a few seconds the Turbo Power Connected message would appear and the screen would turn off. Then the screen would turn back on within 30 seconds and it would repeat the cycle of attempted charging but without a gain in battery %.
Finally I took the USB portion of the charging cable and plugged it into my computer and it started charging with the message indicating that it was a "slow charge". I can't recall the exact wording. After about 2 hours it was charged to 100%. I am waiting until the battery is closer to 50% before trying to charge the phone again to see if the problem still exists. After 10 hours, two of which I was checking email and listening to podcasts, the battery is still at 87%, so there are no apps causing excessive drain and the battery is holding its charge as usual.
I am running Oreo 8.1.0 with the October 1, 2018 security patch. I regularly clear the cache after each update and even did so yesterday in case that would help.
Steve