If your Metamask extension is not displaying the right balance for ETH try one of the following:
1. Switch networks up top by clicking on "Main Ethereum Network", selecting a Testnet, and then switching back again.
2. You can also try toggling between accounts (if you have multiple).
3.Another option is to fully close your browser and re-open.
4. Install Metamask using another supported browser (Firefox, Chrome, Brave)