Run First Aid on the hidden Container. Within Disk Utility you may need to click "View" and select "Show All Devices" so that the physical hidden Container appears on the left pane of Disk Utility. Even if First Aid reports everything is "Ok", click "Show Details" and scroll back through the report to see if there are any unfixed errors listed. If there are any unfixed errors listed, then try running First Aid from Recovery Mode, otherwise you will need to erase the whole physical drive and restore from a backup or clone.
Most likely the SSD is failing. The best way to determine this is by installing macOS to an external drive and booting from the external drive. Make sure to mount the internal drive and wait to see if the internal drive disappears. If it disappears, you will want to see if the physical drive is visible within Disk Utility (use the method above so that the physical drives appear on the left pane of Disk Utility). If the physical drive no longer appears within Disk Utility, then it means the SSD is failing. Many times an SSD failure can be triggered by sleeping & waking the computer since many times the SSD won't go ready again. You can also try copying files to the internal drive to exercise the drive to see if it will trigger a failure.
You can try running the Apple Diagnostics to see if any hardware issues are detected. If you can boot the Mac with a full macOS (internal or external drive), then you can run DriveDx to check the health of the SSD. Post the complete DriveDx text report here using the "Additional Text" icon which looks like a piece of paper. Unfortunately the Apple SSDs don't contain too much useful information in the SSD's health report, but it never hurts to check for clues. Most times the only way to confirm an SSD failure is by the previous method I described by booting from external media while waiting for the SSD to disappear from the bus.
