Witch 4.3.4 (release notes) is out today, and it resolves an issue in macOS Catalina where Witch’s preferences layout was misbehaving: The tab bar would jump around on the screen as you moved from tab to tab, sometimes getting in a state where you couldn’t see the tab bar at all.
It seems that, at some point very late in the Catalina betas, Apple disabled third party System Preference panes’ ability to resize the System Preferences window—Witch used to do this as you switched between its tabs. This update uses a fixed window size for all of the tabs, so the tab bar no longer jumps around as you switch between tabs.
Note: If Witch isn’t working for you at all in macOS Catalina, it’s most likely that you’re running into a glitch with the system’s file quarantine flag. Please read this blog post for the details and the very easy (if geeky) fix.