Yes, I experience this on Android. My solution is to only enable syncthing when the phone is charging (it’s in the settings) but my PC being on and my phone being charged doesn’t usually happen at the same time, so I have another computer in my network act as another node in my syncthing network. This way every night when I charge my phone everything from my PC is synchronized to my second computer, which is always on and can synchronize to my phone.