Before logging in to Phase 2 content, make sure to update your addons. Phase 2 brings with it many Addon API changes, which impact most addons that have UI elements.
These changes are the same that happened with the Dragonflight launch in retail and are now arriving in Classic Wrath. These changes were testable during the Heroic+ and Ulduar testing these past few weeks.
You can find up to date addons in individual repositories and on sites like WoW Interface and CurseForge.