[Full Changelog](https://github.com/matrix-org/matrix-js-sdk/compare/v6.2.0...v6.2.1) * Bring back backup key format migration [\#1399](https://github.com/matrix-org/matrix-js-sdk/pull/1399)
[Full Changelog](https://github.com/matrix-org/matrix-js-sdk/compare/v6.2.0...v6.2.1) * Bring back backup key format migration [\#1399](https://github.com/matrix-org/matrix-js-sdk/pull/1399)