XPS 13 9370 Input Lag When Left Plugged In

I have a new XPS 13 9370. It has this problem with USB C chargers when left for a long time that input gets quite laggy. The only charger that I've never seen this issue with is the OEM charger that came with the laptop. The issue can only be fixed by unplugging, shutting the computer down and starting it up again.

One of the chargers that expose the issue is a Dell PH45W17-CA. I've had the issue with and without the ferrite bead on the laptop end of the charger.

I don't think it's an issue with the OS, because today I tried rebooting while charging from a 30w USB C PD charger. I forgot to unplug the laptop before rebooting, so when it started again the BIOS threw a warning about charging with a 30w charger being slow. While in this screen, the mouse and keyboard were extremely laggy--so it seems like it's a hardware issue.

It could be an issue of my 120v, 60hz (USA) outlet voltage drooping--I've only experienced the issue in my home, which is an older building. The lights occasionally dim when I introduce a large resistive load (eg: a space heater). I've never left the laptop plugged in for a long time any other place. The only times I've noticed it, I think the laptop has gone to sleep before it happens. I've never noticed the issue with the PH45W17-CA when running from the battery pack.