First of all let's talk about Removed features:
Developer Tools experiments Flag removed.Enables Developer Tools experiments. Use Settings panel in Developer Tools to toggle individual experiments. – Mac, Windows
Now the New features/Changes added:
Previously they were scattered here:
This update was delayed for 1 week. I hope Edge canary channel's update cycle returns to the normal periods and we see daily/nightly updates again.
That's it, head over to the Official What's New Microsoft page for more info:
A note on PDF inking, I still have those additional colors & thickness option. I don't guess it is a Controlled Feature Rollout?