You're looking for information on a specific theme for Rainmeter, a popular desktop customization tool for Windows. Here's what I found:
site:deviantart.com "Big Sur RC1" fediafedia
fediafedia big sur rainmeter
The Big Sur RC1 for Rainmeter is a comprehensive suite created by prolific interface designer fediaFedia that transforms the Windows desktop to mimic the aesthetic of macOS Big Sur. First released as a "Release Candidate 1" (RC1) in April 2021, it evolved from the popular Omnimo UI framework to offer a standalone, widget-based experience. Key Features & Design
Big Sur RC1 for Rainmeter by Fediafedia on DeviantArt