Check the box beside Always allow www.roblox.com to open links of this type in the associated app, and click on Open Roblox It should fix the issues you are facing with the white screen on Roblox.

Roblox is now available in open beta on Meta’s Quest VR headsets. Roblox and Meta say there are a few known issues, but if you want to check out the social metaverse platform in VR, now you can ...

If KRNL-Injector failed to find the Roblox process, delete KRNL App data and see. If that doesn't help follow the solutions mentioned in this post to resolve the issue.