Ubuntu is growing faster on Windows 11 than on native Linux PCs, says Canonical
(www.windowslatest.com)
It could be.. But if we're speculating, it could also be the opposite. For example if someone has software they really need Linux for, thanks to WSL they don't need to switch or dual boot. Additionally, if someone uses WSL and it gives them a lot of trouble, then it might also give them the idea that this is because Linux is bad.
WSL is to Window users kind of what Wine/Proton is for Linux users. It's not exactly the same because people have more reasons to want to ditch Windows, but I doubt Wine/Proton is a stepping stone to full Windows for Linux users :)