What can linux write to a flash drive?

Question

linux

Very often it happens that I insert a flash drive, do nothing with it (I don’t throw off anything, I don’t open anything), and when I try to extract (safely remove) Ubuntu writes “Do not turn off writing data to <flash drive name> until the end of the recording” and the indicator on Flash drive flashes rapidly.
And the indicator starts blinking just when I try to extract it. That is, the recording starts exactly when I try to extract.
What is this phenomenon? and what if I don't want any data on the flash drive to be modified?

Answer 1

At least the file access time is updated if you have any tracker running in the background.
So that nothing is written, you need to mount the USB flash drive in ro mode.