Keeping Obsidian open on Samsung mobile devices

1. Go to the Recents page (swipe up and hold if using gesture navigation, or tap the III button if you’re using navigation buttons).
2. Tap the app icon above the app preview/card.
3. Tap Lock this app / Keep open.

For me, on my Samsung S22 this prevents Obsidian from closing, and switching to Obsidian is always instant.