I reviewed a suggested edit to a tag wiki and decided to click
Improve. I wrote some text (at https://unix.stackexchange.com/posts/39283/edit?improve=true), then submitted my edit. I was brought to the page https://unix.stackexchange.com/posts/39283/edit-submit/4bdaca9d-92ce-46bf-a705-c4173a590824 with a content identical to the 404 page.
I think the suggested edit, which created the tag wiki, was approved between the time I clicked
Improve and the time I clicked