We have upgraded MathWallet Extension to V4.0.0
This new version will support more than 200 blockchains, including all EVM blockchains, Bitcoin, Polkadot(substrate-based), and Solana.
But some chains are no longer supported in MathWallet Extension V4. You can export the private keys for these unsupported chain wallets through Settings – Keys.
And if you'd like still using the V3 Extension, you may install:
Edge Browser Extension:
https://microsoftedge.microsoft.com/addons/detail/math-wallet/dfeccadlilpndjjohbjdblepmjeahlmm
Manually install V3:
https://mathwallet-public.s3.us-east-2.amazonaws.com/extension/mathwallet.zip