https://github.com/ma1uta/ma1sd/issues/3 Allow extended character sets for backward compatibility.

src/main/java/io/kamax/mxisd/auth/AuthManager.java

@@ -140,7 +140,7 @@ public class AuthManager {
                 }
 
                 try {
-                    MatrixID.asValid(mxId);
+                    MatrixID.asAcceptable(mxId);
                 } catch (IllegalArgumentException e) {
                     log.warn("The returned User ID {} is not a valid Matrix ID. Login might fail at the Homeserver level", mxId);
                 }