Trying to buy the game when logged in and already owning the game signs you out of minecraft.net

The bug

When logged into an account that already owns Minecraft (Java Edition) and trying to buy another copy of Java Edition, the user is logged out of minecraft.net instead of being redirected to the Java Edition download page.

This is a major inconvenience for players returning to the game, making them believe that they need to create a new account and repurchase the game.

To reproduce

1. Log into an account that owns Minecraft
2. Go to https://www.minecraft.net/en-us/store/minecraft-java-edition
3. Click "Buy Minecraft"
   → You are logged out