Iris 1.6.4 for Minecraft 1.20
It's 1.20 time.
This release adds support for changing the color space that is drawn. (This does not enable HDR.) It also contains quite a few bug fixes.
A more detailed changelog is available for those interested: https://github.com/IrisShaders/Iris/blob/1.18.2/docs/changelogs/1.6.4/full.md