mac mini m1 2020 stopped recognizing my second monitor

I have a Mac Mini m1 2020 with dual external monitors. One (a Samsung monitor) is hooked up to the HDMI port and the other one (an Acer monitor) is hooked up to the USB -C port. They were both working well together for quite a while and suddenly the second monitor stopped being recognized. They both still work perfectly if I disconnect the other one (so if I disconnect the samsung monitor the computer recognizes the acer monitor, and if I disconnect the acer monitor the computer recognizes the samsung monitor). It's only when they are BOTH connected that the computer then only recognizes one of them (generally the one that is connected via USB-C). I've tried the "Detect Display" option in system settings and I've tried new cables. The mac mini is up-to-date with system updates, though I can't tell when the last update was done (I have the mac mini set to autoupdate).

Does anyone know what might have happened?