For the quick-open button to stop showing on every page whenever you highlight a piece of text you should just:
Open your Collabwriting Extension
Press the ⚙️ icon on the top right
Scroll down and check the "Hide quick open button" setting item
After this Collabwriting Quick-Open button won't show anymore on web pages you visit.
You can achieve the same result by right-clicking on the quick-open button and choosing "Never show again." This action will have the identical effect as described previously.
Watch the tutorial here: https://www.youtube.com/watch?v=shLGPaj1b-M&ab_channel=Collabwriting