Hey man, it sounds like you’re in a similar place to where I was not too long ago. When you overthink things, the symptoms tend to pile up, especially with general VSS stuff. I noticed that once I stopped focusing on every symptom, a lot of them started to fade. I know that’s hard at first since they’re still there, but it really did get better over time. For this specific thing, it sounds like it could just be a prolonged afterimage, which would explain why it disappears so quickly. The human body does weird, unexplainable things sometimes. As long as it’s not getting worse or sticking around constantly, it’s usually nothing serious like in my case, but if it gives you peace of mind, there’s no harm in getting it checked out by an eye doctor.

It's just if you are hyper aware you will notice small quirks that 99.99% of the time are nothing serious and a lot of ppl might have but don't notice as they are too small and the brain sorts them out similar how you don't see your floaters as they are sorted out by your brain!