Nebula Dreams
I hope you don't take this the wrong way.
The thumbnails of each game on Steam are very important because that's what someone who doesn't know anything about the game will first see AND if they feel attracted to it, they'll click on it and
then they'll see the game page with all the previews and the synopsis you wrote.
For example, when Steam recommends "similar games" to someone who plays a lot or buys visual novels, they will only see that thumbnail, so I would recommend that you take an afternoon in December weeks before release and change yours.
Why? Because it's pretty bad and doesn't make you want to click on it, you can only read the name of the game with those white and red letters that stand out, but the background is almost unrecognisable because it's so dark and you can barely see Mina there.
You should look for something that grabs your attention, the famous click-bait like many YouTube videos.
I'll give you some examples in the spoilers:
My best wishes


!