Currently you have to manually do a full uninstall and then find the ISO/Installation media of a previous version, and install that from scratch, when you encounter a show stopper after an upgrade.
Provide a more efficient and automated way to revert to a previous version.
For example: provide a menu to select which previous version is required and then do the download, uninstall, install with minimum user interaction - in the same way as upgrades are performed.
I thought I tested 3.3 for long enough but just found a nasty symbology issue in a map/layout created in 3.2.
I keep older PCs alive and could grab one with a 3.0.1 install and get the job done in 5min (after struggling with a 3.3 symbology issue for an hour).