In the past, users could only connect up to 4 devices or Brave user profiles with Brave Rewards to a single custodial account (Uphold, Gemini, bitFlyer). This was known as the "linking limit".
As of May 2022, linking limits have been removed.
Why am I still seeing a "linking limit" error?
If for some reason you are still encountering a linking limit error while trying to verify Brave Rewards, you can open a support ticket here.