While Translucent window plugin is enabled in Obsidian settings, there is no translucency after launching the app until you press Cmd+R or put Obsidian in full-screen mode and then back to normal view.
Obsidian right after launch:
Obsidian after pressing Cmd+R:
Environment
- Operating system: macOS Big Sur
- Obsidian version: 0.9.22, installer: 0.9.20, no CSS