OLED dim on every other power up - u8g2 library - SH1106

In a project I'm working on the OLED is displaying some weird behavior -

I will power it on one time, and the screen is working as expected, at maximum brightness. Then I turn it off, and power it back on, and the screen is very dim.

I'm not sure what the problem could be, but I would love to be able to work it out.

I have resoldered all the Caps on the back of the oled board, so the charge pump circuit should be working properly.

As I mentioned in the title, I am using the SH1106 SPI module with the u8g2 library

Right, pictures of your setup taken clearly in bright light, a description of the parts, power supply ...

Power supply is 9v regulated down to 5v with a UA78M05CDCYR, 10uf caps to ground on both the 9v and 5v sides of the regulator

The 5v goes to the OLED, with reset connected to that power rail as well. Another 10uf electrolytic cap and 1uf ceramic cap to ground.

I'm not sure how much pictures will help, its all on a professionally fabricated PCB, but I can take pics of anything specific you think would help