2022 October, 28
The next version of Jekyll V5 will open doors but contain breaking changes. A major version changes significantly, and much work is expected to make the previous code of a Jekyll site work in version V5.
End of October 2022, the development team of the Jekyll Project decided to continue on version V4 in favor of releasing a V5 version too early. The upcoming versions of Jekyll V4 continues by v4.4.
A tentative roadmap for Jekyll V5 has been set up at the GitHub repository of Jekyll by one of the maintainers of the Jekyll project Ashwin Maroli.
To give everyone a glimpse of the probable outcome, the active discussion is available at the Jekyll V5 Roadmap.