LVGL (in zephyr) drawing lines which are larger than the width in the style


I am having trouble with the Zephyr port of LVGL in that it is drawing lines that are “smudged” (ie 1px lines are not actually 1px wide). This doesn’t happen in the TFT simulator which is at the same version (v7.6.1) with the exact same widget code. I have filed a bug here on the zephyr github page:

I realise that this is probably not an LVGL issue, but has anyone seen an issue like this before? If so, could you give me any hits/tips/ideas on what may be causing this behaviour?

TFT simulator:

Actual OLED display connected to MCU:


I also just noticed that the fonts don’t match, even though they are both using unscii_8…