Are previously downloaded Steam games transferable from Windows to Linux?

https://reddthat.com/post/4370732

Are previously downloaded Steam games transferable from Windows to Linux? - Reddthat

I’ve backed up many of the Steam games I had installed in Windows. Am I able to use these on Linux or do I need to re-download them?

Yup, you’ll be fine. If a game has a Linux version though, you’ll still need to download some portion of it. By the way, just don’t use NTFS to play on Linux.
In my experience it works perfectly fine as long as you perform the steps outlined here, as per Valve’s official recommendation. The section about preventing read errors is particularly important, but the whole thing is worth a read.
Using a NTFS disk with Linux and Windows

Compatibility tool for Steam Play based on Wine and additional components - ValveSoftware/Proton

GitHub
Might be useful for dual-boot users or the people in transition, but doesn’t worth the hassle for exclusive users. However it will still cause some problems one way or another because it’s just a workaround.
THANK YOU for this!! I fought with ntfs in a new manjaro install last weekend and just could not friggin figure it out! So excited to see a valve better fix!
No worries, glad it helped!