[Maxximou5]

From what I understand you are setting the values incorrectly. It is a bit confusing since the meaning of the commands has changed overtime in CS:GO and in CS2.

If you don't want it to change drastically you would want:

bot_difficulty 1 // Defines the skill of bots joining the game. Values are: 0=easy, 1=normal, 2=hard, 3=expert.
bot_autodifficulty_threshold_high 20 // Upper bound above Average Human Contribution Score that a bot must be above to change its difficulty
bot_autodifficulty_threshold_low -20 // Lower bound below Average Human Contribution Score that a bot must be below to change its difficulty

If for offline, add:
custom_bot_difficulty 1 // Bot difficulty for offline play. Values are: 0=easy, 1=normal, 2=hard, 3=expert.

I don't know of an option to disable changing of difficulty permanently, but perhaps someone else knows.