@lmx Good question. I am unsure whether ACP->Settings->Uploads affects url images. I think it does but been a while since I tweaked those knobs.... 🤔
Have you tried/tested any of those that relate to images?
You can disable it here: https://github.com/designcreateplay/nodebb-theme-lavender/blob/master/static/lib/lavender.js#L42
Not sure about changing the width to 100%, you'd have to ask @baris
Haha totally missed that, was looking in the LESS