Starting March 11, 2020, new wikis use the Unified Community Platform (UCP). Fandom has also started to convert some older wikis to UCP. UCP wikis currently have modified functionality, and are missing some legacy features. Fandom is continuing to work on adding/porting some missing features. For a user-compiled list of bugs, please see this page.
UCP wikis are significantly different from legacy wikis. Since the platform is still in development, there is essentially no documentation on what is available and how to use it. The best that can be done is to use knowledge of the legacy platform to guess and check what can be done on UCP.