You have a legacy seed phrase phrase (24-words) that Brave used to provide in old wallets. I don’t think there is a way you can import same accounts in Metamask using this. Importing will only work with brave wallet (when you select “import using legacy seed phrase”).
You have 2 options-
- Send your funds to a newly created Metamask wallet (this one will have a 12-word seed phrase). This I think you have been unable to do so. Can you post a screenshot of the error that you get? Also make sure your Brave is updated and using latest version of Brave wallet
brave://components/. - Create a new wallet in Metamask and and import your each account on Brave Wallet using Private keys.
See here for more info-