I have two U2722D monitors. After less than a month, one began flickering with horizontal lines. When running the diagnostics, this was only visible on the grey screen. Dell warrantied that monitor and the replacement seems to be doing well so far. My second U2722D has now suddenly developed the same exact issue. For context, I am running both from an XPS 15 through a Dell Thunderbolt dock and both U2722D are powered through a UPS.

Is this a known issue?