I think you’re confusing the topic here. This post is regarding “A Timely Invitation” which is offered to a character when they open their Anniversary mail. Your character is currently on that quest. It is just a “Go see Chromie in the Caverns of Time” directions quest.
It does not place you in timewalking and does not affect your access to dungeons.
You may be experiencing something else, discussed here:
https://us.forums.blizzard.com/en/wow/t/level-50-stuck-timewalking/702923/4