on closer inspection I tend to agree with you, there is indeed a white line on your leaf.
if you can rule out any issue with your resources supply and space controls its likely a variegation.
I almost wondered what strain, but now I dont care too much
This is the plant in natural light. It's starting on another one of it's leaves as well. I tried looking more into it but the only thing coming up is leaf miners. The other pictures of plants with that issue have squiggly white lines everywhere and looks nothing like this.