Bootloader problem on Arduino Uno?

Since today, my Arduino Uno (using Arduino IDE version 1.8.13) lost the capacity to store a sketch upon physical disconnection (does not include button reset).

This means, the sketch works properly but when I unplug it and plug it back again, the Arduino will act as if I uploaded a blank sketch by blinking 3 times fast repeatedly.

To check this, I tried several examples like "Blink" on Windows 10 and Ubuntu and repeats the error.

I feel there is something wrong with the bootloader or something like that, but I’m finding hard to understand some concepts.

Does anyone recognizes what is happening on the Arduino? What can I do to address the problem?

Summary:

• Uploads fine.
• Works fine.
• Resets fine.
• Hard-resets INCORRECTLY (can’t plug and unplug and expect the program will still work).
• Keeps working good until loss of power.