Can you try clearing the cache/site data for the site (lock icon in the address bar Site settings --> Clear data) and then see if the 404 message disappears?
@TheGreighCanary,
Well that is interesting…I’ll reach out to some team members about this. Would you mind providing some additional examples?
Also, can you try going to Settings --> Help Tips (scroll all the way down) and toggle the Show Wayback Machine prompt on 404 pages “off” and tell me if the notification still appears?
@TheGreighCanary,
Thank you for confirming. I’ll inform the team of the behavior so they can review it. Until then, I hope keeping the option toggled off is okay.
@Mattches I found at least one. I’m sorry about leaving this. I haven’t had time to submit any more of them. But one for me at least is https://sitekit.withgoogle.com/. It’s used to setup Site Analytics and other things with Wordpress.