Microcontroller default state problem
What does &quot;High Impedance&quot; state of a pad look like?
Output driver, off.
Input receiver, off.
pull logic, off.
ADC channel selection, off.
All you have are the diodes.


What does default state actually mean?
The state set at reset (falling edge on reset pin) until changed by software (eg: your software of bootloader)
The ALT columns refers to other options the you can activate on the multiplexer behind do and ind.

Why am I getting 0.7V or 0.8V instead of the required 2.5V when my Microcontroller is not programmed?

There is circuitry on the board you are missing. The leakage on pins is only max 0.5 uA, which would be the equivalent of a 10 M ohm load on your divider.
Or the part isn't as empty as you think.
Or, you have destroyed the pad by ESD strike.