device boots into recovery every time I reboot, probably because playing with a system app
There can be several possibilities so let's check step by step

check whether your volume kye is not pressed ( what happens if your device has fallen down by the volume side there are chances that the volume button would have got pressed.

2.if the 1st is not your problem then try checking your Rom setting if your device is rooted. there are chances that while flashing custom rom your rom would have been not flashed properly so the device gets into a loop and is not able to load your rom.

if not rooted, then there are chances that the problem is with your rom.

solution
Try hard resetting your device this may fix it.
or reinstalling your device rom.
some time while restoring the device can also cause this problem. so I would suggest checking your rom once. if still, the problem persists comment down will try some other fix.
wish you luck..