What gives? It used to be that I could look up a thread from a decade ago and find it. Now all "my threads" in the vgchartz profile section are missing. (Edit: And now they are back.) And older threads that are linked to from Google just send you to the main page. Is vgchartz deleting older threads now? Why can't I search for a thread that's older than 90 days? 

Search history is the same for me,  (only the last 90 days which is a bit annoying) but I checked and I can still access threads going back a few years.

A while back, there was a hack that deleted/corrupted a lot of older content, so that may be what you're experiencing.

I find it more than annoying. I hate how Reddit, Facebook, Youtube, etc. all make it nearly impossible to find a conversation from even a few days ago. So then people just get to post the same lies over and over again. Or people have the same conversations without realizing that it was already discussed a few days ago. And then nobody gets the benefit of looking back at their old posts and things they said from years ago. So no benefit of reflection. No history. 

The 90-day limit in the search page has been there ever since I joined the forum 12 years ago. Oddly enough, it actually will bring up threads older than 90 days if you selection the 90 days option, but it's kind of weird how it sorts them, and you only get a single page of results, so you need to be really specific.

Also, if you get to a thread through Google, if they link to a page past the first one, it might not show because users can customize the number of posts per page. Google always links to thread pages by the default 10 posts per page, so if you have it set to 25 per page like I do and you find a link to a tenth page in a 100-reply thread, it won't load because replies #91-100 will be on the fourth page in your settings, and since that tenth page wouldn't exist in your settings you just get redirected back to the home page if you try to load it. You would need to alter the URL to start at the first page and go from there, or guess which page the post would on under your settings.

Unless your post history got wiped in that hacking incident from a couple of years ago (I had over 7000 posts prior to Oct. 2022 wiped from existence, including posts with charts from old NPD threads), your posts should still be there, but the site can be screwy when searching both within the site's own search page and through Google.

This is because it looks at threads that have been updated in the last 90 days (as in, new posts), not created during that timeframe.

I just did a search for posts of my own containing "PS4" as a search term and it brought up some threads that haven't had new replies well past 90 days ago, a couple of them not having had any new replies since 2023. And the way it sorts them is weird. It seems random.

Looking at your search, it also ignores the sorting options completely. I tried to find where where the issue originates, but the website writing is so convoluted that I couldn't manage to do so