Beginner Question - Environment boot page

Sorry if that has been addressed already:

When starting the Picocalc, the screen bottom message shows ‘Stabilizing SD Card’ - that does not sound very encouraging - what does this mean and what does the Picocalc do?

Then the boot page has the various environments. Upon choosing picomite for example, the screen bottom message shows “STAT: flashing firmware”. What is actually flashed, from where to where? As flash memory has only a certain number of writes before becoming unreliable, is that a concern? Better store a backup of the original SD card?

Thank you