This a stable release.
https://github.com/anza-xyz/agave/blob/v4.0/CHANGELOG.md
What's Changed
- v4.0: Give write permissions to release jobs (backport of #13178) by @mergify[bot] in #13201
- v4.0: entry: Disallow ticks with 0 hashes (backport of #13231) by @mergify[bot] in #13237
- v4.0: blockstore: Disallow deshredded empty entry batches (backport of #13232) by @mergify[bot] in #13240
- v4.0: perf: cache delegated stake for vote account upsert (backport of #13229) by @mergify[bot] in #13242
- v4.0: Drop incorrectly sized nonces on leader (backport of #13233) by @mergify[bot] in #13244
- Bump version to 4.0.3 by @github-actions[bot] in #13212
Full Changelog: v4.0.2...v4.0.3