I saw this in nearly all of the old growth.
In researching this I found that it could be eggs of a leaf-miner, or simply just sun damage. I wanted to confirm if this is something to worry about, and whether it has anything to do with nutrient deficiencies as well. Thanks!
It could be many things, but you're probably best off treating it like edema (which it could be; if it's not edema, it probably would contribute to it a lot, if conditions were favorable for edema). I've had that issue when starting tomatoes indoors under lights. I've never had it with other methods of starting them.
I would suggest such as the following: increasing ventilation, reducing temperatures, don't get the leaves wet when you water, give them extra potassium, etc. For me, the issue went away after the transplant, with the new growth.
If your plant is already in its final destination, I might suspect humidity being the issue. I wouldn't worry about it too much, unless something else starts to happen.
Possibilities (besides edema) include things like mites, scale insects, downy mildew, parasitic algae, etc.
It's not sun damage, but those areas could be more prone to sun damage in future.
I don't think it's leaf miners.
Awe, you sweetie! I wouldn’t have looked twice at this, myself. DEFINITELY not sun damage; and the coloration on this leaf looks great, as does the rest of the visible foliage in your pic — meaning, short of other symptoms, you’re not seeing a nutrition issue here.
Looks to me like you’re doing a great job with these plants! :)
