Undeleting is still available from the page tabs. Vector hides it under "More":

I think we should just hide this non-functional link and let people discover that it is also present in page tabs. That is a much more reasonable place for it anyway – in the same place as the "Delete" link, same as other functions work (e.g. "Protect"/"Change protection").

The difference between the message on top of the page and the undelete option in the page tabs is that the second doesn't tell you whether there are deleted revisions until you invoke it.
This actually is more or less a page notice (read it as "The page you are going to create has been deleted before. Do you want to start from scratch, or do you want to undelete these revisions?") and thus should be shown together with the other page notice.

The "delete" option is also hidden behind the "Publish" button.

@GoEThe That's a known issue affecting the new Vector only: T264379

What's the reason for css-code:

.ve-init-mw-desktopArticleTarget-uneditableContent {
pointer-events: none;
}

that makes clicking the links impossible, by setting it to "auto" fix that.

Any chance this could get prioritized? I originally filed T187417 for this 5 years ago and it's still creating extra work for me almost every day.