I guess it was my MC (Thief) with 12 charisma + Expertise in persuasion & deception + Guidance cantrip. Moreover he never rolls a 1... I would remember that.
12 Charisma gives a +1
Expertise gives a +4
Guidance gives a +1 to +4
Total: +6 to a +9
It's consistent that you rolled a natural 1, which was then bumped to a 9 in Larian's (overly flashy) animation that presents your total. Given that your screenshot shows "Failed," the addition of modifiers has already happened and that number shown on the die is your total (roll+modifiers), not your raw roll. With a total of 9, there's a 33% chance you rolled a natural 1 (and guidance was a +3).
If you're absolutely sure that the original roll wasn't a 1, then idk. But that's my guess.