Gary Illyes from Google said on LinkedIn that Google Search Console doesn't "keep (almost) any data for un/de-indexed." He added, "There's also an element of "what if the URL comes back", but that's less relevant."
This came up when Adam Gent "noticed that Google can drop the canonical data (both user-selected and Google-selected) for pages that were indexed and moved to "crawled - currently not indexed"," he wrote. He asked, "Is this a reporting error or does your index eventually just drop data points like the canonical metrics?"
Gary confirmed this is the case. Gary wrote, "We don't keep (almost) any data for un/de-indexed, this Search Console has nothing to show."
Adam Gent replied, "I've seen pages de-indexed with canonical data but my assumption is that at such a scale, it just takes time for the data to be slowly removed from the index for each page. Which is why some have data and others don't."
Gary responded to that saying, "I don't wanna go into the details cos it will confuse everyone and my grandmother unless I give even more context that will be equally confusing without some other context, but yeah, that's basically it. There's also an element of "what if the URL comes back", but that's less relevant."
Forum discussion at LinkedIn.