Here are the release notes for the SDK version 2021.7.7.13756.

We have around a hundred scripting additions, fixes and improvements in this release. We've added support for changing uploaded UI element colours to match application via Lua script. Tooltips can now be added to any UI element automatically. Also added the SimpleStateMachine for creating interactive content without scripting. The Editor Pack will now check for lightmaps for export if baked lighting is detected in the scene.

That's just some of the highlights, the full list is below.