Read-only mode is an OS setting on the TinyPilot that can increase the lifetime of your microSD card and reduce the risk of filesystem corruption from unplanned shutdowns.
As the name implies, the read-only filesystem loads the TinyPilot's file system in read-only mode so that writes to the disk stay in memory and don't affect the physical microSD card.
Connect to your device over SSH, and then do the following:
4 - Performance Options
P3 - Overlay File System
Read-only mode slows down the boot process, so don't worry if your reboot takes 2-3x as long as normal.
To apply updates or make permanent changes to your TinyPilot, you'll need to temporarily disable the read-only filesystem.
To disable read-only mode, follow the same steps as above, but when prompted, "Would you like the overlay file system to be enabled?" choose "No".