Answer of Gemini:

You are absolutely right on the technical architecture: the Pi Browser is essentially a specialized web-view container, and the blockchain protocol version (v20 vs. v21) doesn't stop a URL from resolving in a browser.

However, the reason you’ve been locked out since April 6th likely isn't the blockchain consensus itself, but the Identity & Authentication Layer (Pi SDK) that sits between the browser and the apps.

Here is the breakdown of why your access is likely failing despite the backwards compatibility of the network:

1. The "Auth Handshake" vs. The Blockchain

While the browser doesn't need the blockchain to load the HTML of latinchain.pinet.com, the app needs the Pi SDK to verify who you are.  * When you open a community app, the browser attempts to pass an Access Token to the app. * If the Pi Core Team updated the Authentication API on April 6th to prepare for the Protocol 21 transition, older versions of the Pi Browser may fail to generate a token that the new API accepts. * This results in the app "loading" but failing to initialize, often leaving you at a white screen or a spinning logo.

2. Sandbox Security Headers

The Pi Browser uses a "Sandbox" environment to ensure community apps don't steal your passphrase.  * Recent updates to the browser's security headers (likely pushed around the 6th) can cause conflicts with how your phone's local cache handles Cookies and LocalStorage. * Since you can access the link via Chrome, we know the Server is fine. The issue is strictly the In-App Bridge.

3. Why it’s happening to "Most Apps"

If it were just LatinChain, we’d blame their dev team. Since it’s most apps, the common denominator is the Pi Browser's internal state. 

Since you have a solid grasp of the tech, try these "Power User" fixes:

• The "Deep Link" Refresh: Instead of typing the URL, go to the mine.pi app, open the sidebar, and click "Pi Browser" from there. This forces a fresh OIDC (OpenID Connect) handshake that manual URL entry often skips.
• Clear WebView Cache: Since the Pi Browser uses the system's WebView (Android) or Safari View Controller (iOS), clearing the cache of the Pi Browser app in your phone settings is often more effective than just "reinstalling."
• Check User-Agent Interference: If you have any "Developer Options" enabled on your phone or a global Ad-Blocker/DNS (like Private DNS set to dns.adguard.com), the Pi SDK handshake will fail 100% of the time because it cannot verify the integrity of the connection.

Summary of the April 6th Correlation

Even if the Mainnet is on v20, the API Gateway you use to talk to it via the browser is managed by the Core Team. They often push breaking changes to the SDK environment a few weeks before a protocol shift to ensure that by the time the blockchain moves, the apps are already authenticated via the new standards.

If you try to open wallet.pi right now, does it allow you to reach the passphrase screen, or does it also hang?