Try disabling the VPN, restarting the device/browser and seeing if the claim button shows up, it’s likely the IP for the VPN is flagged because too many people have used it. You gotta understand from the servers perspective all they see is your wallet and a bunch of other wallets all wanting to claim bat from seemingly the same location which looks really sketchy. It makes it seem like someone is exploiting the ad rewards with a bunch of different devices.
Even I didn’t get the claim option infact they asked me to DM info about Wallet and closed the query without responding to it. Mostly I guess the rewards are being misused by brave and its developers