As of Q1 2020, MetaMask has officially stopped injecting Web3.js, and has updated the way you access the current provider. Here’s how to make sure your dApp doesn’t break, and how to make it more compatible with the rest of the ecosystem. The New, More Compatible Way According to this article: Breaking Changes to the MetaMask Inpage Provider
On January 13, 2020, we are removing some legacy features from the MetaMask inpage provider .medium.com