Q1 is a 662k 3v3 regulator (the regulator the seller was referring to).
I tried to use the Oled on a 3v3 system ad got the same results unfortunately. Same on the nano, uno and standalone 328p through a LM317 set for 3.31V. I don't know what to even think might be the issue. I have 3 of those displays and all cause the same issue