Hi, I had the same problem. Basically Uphold only allows to connect 4 devices to it. However, changing your OS and/or reinstalling Brave, makes Uphold to consider it a new device even if it’s the same, making you reach your limit and letting you unable to reconnect your wallets.
Sadly, theres no function to unlink devices by yourself, but its being developed:
Meanwhile, you have the alternative of requesting support for ONE of your old devices (not sure if only one per account or only one per request) you are not using to be disconnected from uphold.