This is a feature release, which includes new features and removes previously deprecated features. The 3.1.x branch is now the supported bugfix branch, the 3.0.x branch has become a tag marking the end of support for that branch. We encourage everyone to upgrade, and to use a tool such as pip-tools to pin all dependencies and control upgrades. We also encourage upgrading to MarkupSafe 2.1.1, the latest version at this time.