What might cause these dark, odd spots along the top of my cat's nose? Doesn't seem to be lentigo simplex, as they appear suddenly and then disappear, + it's happened twice

https://ibb.co/5hqPDyC3

My cat has had dark spots appear along the top of his nose/in the fur that meets his nose, twice now. It doesn't seem like they're nose freckles, because they showed up pretty quickly over the span of a week or so, just 1 at first and then more. It also happened once before a couple months ago, with less spots that time. The spots went away after probably 2-3 weeks that time.

What might be odd is that the 1st time they showed up, it was around the time when I'd been suspecting he might be having some sort of possible feline herpesvirus/other viral flare up. At that time, he'd been having just very mild nasal congestion sometimes, and possibly slightly less energy, along with stomach issues (which I felt were probably due to his regular issues but I wasn't sure). The very day he came home from a vet visit for those issues, he ended up with a cloudy eye/third eyelid showing that evening. I was never quite sure whether this may have been from some possible viral thing, worsening flare from the stress of the vet, or if he'd just physically bumped his eye at the vet during a little freak out where he'd been jumping around.

The vet didn't actually test for FHV or anything for whatever reason, but she gave him antivirals just in case because of my worries. But it's odd to me, because if he had in fact had some viral thing going on back then, I wonder if the nose spots were related to it somehow. This week, I've noticed it sounds like he's slightly congested again. And it's odd, because of the dark nose spots popping up again recently. FWIW I didn't notice any big quick change in his symptoms with the antivirals, he just eventually went back to normal and the spots went away by a few weeks.

The only other possible cause I could think of is nose scratches from playing with my other cat. But I haven't seen them playing rough, and it'd be odd for them to just show up in this spot twice and to not show up other times? I haven't seen Panko himself scratching his nose to cause them, although of course it's not impossible he did it when I wasn't looking.

Does anyone know what could be causing these spots? Have you ever seen anything like this on a cat?

(Note: I know the url looks kinda funky, it's just a short url for imgbb.com. I don't have imgur app anymore so googled somewhere to upload it)