OctoPrint USB disconnects on Linux Mint at midnight?

A new and bizarre issue has emerged on my Linux Mint server that seems specific to my Ender 3 and OctoPrint. Every night at midnight, regardless of whether a print is running or not, the USB connection to the Ender fails and restarts. (See screenshot from my Telegram OctoPrint plugin.) I’ve tried setting usb.autosuspend to -1 in GRUB, but that doesn’t seem to help.

I’m completely stumped and could use some advice. The failures are far too scheduled and predictable to be a random hardware failure. A relevant chunk of /var/log/syslog is included below for reference.

May 5 00:00:03 borgcube systemd[1]: logrotate.service: Succeeded. May 5 00:00:03 borgcube systemd[1]: Finished Rotate log files. May 5 00:00:03 borgcube kernel: [93921.837884] usb 1-5.4: new full-speed USB device number 9 us ing xhci_hcd May 5 00:00:03 borgcube systemd[1]: man-db.service: Succeeded. May 5 00:00:03 borgcube systemd[1]: Finished Daily man-db regeneration. May 5 00:00:03 borgcube kernel: [93922.059024] usb 1-5.4: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.63 May 5 00:00:03 borgcube kernel: [93922.059026] usb 1-5.4: New USB device strings: Mfr=0, Produc t=2, SerialNumber=0 May 5 00:00:03 borgcube kernel: [93922.059027] usb 1-5.4: Product: USB2.0-Serial May 5 00:00:03 borgcube kernel: [93922.066323] ch341 1-5.4:1.0: ch341-uart converter detected May 5 00:00:03 borgcube kernel: [93922.066896] usb 1-5.4: ch341-uart converter now attached to ttyUSB0 May 5 00:00:03 borgcube mtp-probe: checking bus 1, device 9: "/sys/devices/pci0000:00/0000:00:1 4.0/usb1/1-5/1-5.4" May 5 00:00:03 borgcube mtp-probe: bus: 1, device: 9 was not an MTP device May 5 00:00:03 borgcube snapd[1104]: hotplug.go:200: hotplug device add event ignored, enable e xperimental.hotplug May 5 00:00:03 borgcube mtp-probe: checking bus 1, device 9: "/sys/devices/pci0000:00/0000:00:1 4.0/usb1/1-5/1-5.4" May 5 00:00:04 borgcube mtp-probe: bus: 1, device: 9 was not an MTP device