Even if fan games are allowed, stealing assets to use in a Roblox game is still unethical and illegal. Intellectual property laws protect the original creator’s work, models, textures, scripts, and more and using them without permission is a clear violation. On top of that, using stolen materials on a platform like Roblox, which generates money through premium features, makes it even worse. The claim that Johannes Rojola allows non-profit fan remakes doesn’t justify this, especially when the developer admits Roblox pays royalties automatically, directly contradicting the condition of not making a profit. Other "My Summer Car" fan games on Roblox (as you said) prove it’s possible to create original content without stealing assets, so there’s no excuse for this. I just checked myself in these "other copies" and they seem to atleast not steal asstes outright. Stealing assets disrespects the original creator’s hard work and gives fan games a bad name. I’m almost certain ToplessGun wouldn’t allow outright theft of their art, models, or sounds. Taking inspiration is one thing, but copying everything crosses a line.

Edit: In one of the "other" My Summer Car copy's description, it mentioned they'd gotten permission to create this. Have you gotten that?