I should have also noticed that I haven’t noticed stunted growth of my tomato plants, or any other seedlings I’ve started. 

I have noticed a “gnarled stem” on my cherry tomato seedlings, which I know is a sign of damping off. They seem to have recovered from this and are growing. In the past, I’ve circumvented this by planting deep so the tomato can grow additional roots.

My tomato seedlings are growing alongside the other following seed starts: basil, thyme, oregano, parsley, peppers (poblano, orange bell, Olympic bell, shishito).
 

You don't likely need to discard any of the plants as long as the main stems remain in good condition and there is at least some foliage near the growing tip. Their health and vigor will likely improve once they get outside (acclimate them first).

It's hard to diagnose the pictured leaf discoloration, but it looks minor and may be due to powdery mildew, which prefers conditions with limited air circulation. Your use of a fan is good, but perhaps it's not circulating the air as much as may be needed (especially if the seedlings are in an area with moderate or high humidity). It will probably abate and be a non-issue once the plants are growing outside, but if needed, at that point you could try using a fungicide labeled for powdery mildew control that is also registered for use on vegetables.

Seedlings with damping-off infections usually do not recover, but regardless of the cause of the initial symptoms, if the plants appear to be rebounding, that's a good sign. Soil moisture may have been a contributing factor (either having gotten too dry at one point, or too wet). The shriveled tip of the tomato leaf pictured suggests physical damage; perhaps it was pinched by something or otherwise partially cut off from the main leaf veins and as such dried out. It doesn't look like a problem and can be clipped off (damaged leaf tissues cannot heal). The potting mix in the photos looks on the dry side, unless you're just about to water them, which may explain why some foliage distortion or marginal desiccation was taking place.

Over the next week or two, acclimate the plants to outdoor conditions by gradually introducing them to more light and temperature swings. (Put them outside for increasing intervals to get them used to these changes.) Put them in mostly shade at first and incrementally get them used for more direct sun, since grow lights indoors are not as intense as sunlight, and leaf sunburn could result if they don't have an adjustment period. Our Hardening Off web page has a bit more info about the process.

Miri

Thank you so much for the thorough response! I'm grateful it's not something like Tomato Mosaic Virus.

Additional photos attached. If these change any conclusions from your first note, please let me know.

Best ~ Mike

Thank you for the additional photos. We don't see any symptoms of great concern, and don't have any diagnostic assessment changes at this point. If the plants develop worsening or new symptoms once they are growing outside, feel free to send more photos at that point.

Miri

You're welcome!