ffmpeg version 6.1 is out: http://ffmpeg.org/index.html#news
It promises a faster FFT/MDCT/DCT/DST processing through a new libavutil/tx library (more information "coming soon").
Other major news items can be found https://github.com/FFmpeg/FFmpeg/blob/master/Changelog
6.1 has been "overdue for at least half a year" according to the development team; 7.0 is still planned for a February 2024 release.