The discussion revolves around issues with the 2.9.0beta2 version and the HeaderSubmenus plugin. Wurzelseppi wants to roll back to 2.9.0beta1 due to problems with the plugin, specifically that it doesn’t display correctly. IAmGav suggests using a different version of the plugin, but Wurzelseppi has already rolled back to the stable version by changing app.yml to version: stable. IAmGav and pfaffman discuss the possibility of rolling back, with pfaffman providing a more nuanced answer. IAmGav, Mark_Schmucker, and JammyDodger report that the plugin works for them, with IAmGav sharing a screenshot of the working plugin.
That’s the easy answer. The more nuanced answer is that you can roll back as long as there haven’t been any database migrations. Then you can put a commit in where tests-passed is. If he surprised if going back you stable doesn’t cause any problems, but I haven’t looked at the commits.
That said, I’d use the stuff that works and upgrade.