Unusual characters on the display - please help

[Paul_B]

@mongol

I am not familiar to level shifters, is it this one?:

For I²C level conversion - but only for I²C level conversion, that is the correct level shifter.

For other purposes, such as driving WS2812 or similar LED strips from 3.3 V logic, you need the 74HCT14 or similar.