Unsafe lifecycle methods

This library uses [unsafe lifecycle methods](https://reactjs.org/docs/strict-mode.html#identifying-unsafe-lifecycles) which may cause problems when [React's new concurrent mode](https://reactjs.org/docs/concurrent-mode-intro.html) is enabled.

The issue does not name any files, tests, or lifecycle methods. Start by locating React components that use unsafe lifecycle methods, then check their behavior under React Strict Mode or concurrent mode. Done means the unsafe methods are addressed without breaking server-side rendering or code splitting, with relevant behavior verified by the project’s existing checks.

Written by the indexing model from the issue text.