I think this is because of their recent February update with their search engine. Google recently updated their broad-core algorithm in its SEO to be improved with Passage Ranking. I've seen this article that explains it very well -- https://www.searchenginejournal.com/google-passage-ranking-martin-splitt/388206/#close

With that update, it is not only your thread that is affected, but the general results from any users who searched with exact keyword on Google. Based on my understanding with Passage Ranking, its algorithm ranks the results based on the overall content of the page independently -- which leads to your 2nd thread page be shown first than the main OP.

There's a discussion that started last year on Google starting to act different.
Back then they were still returning for me relevant pages. Lately I started getting basically crap. Now I know why.

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I've done exact search for some areas in that old post and.. woah, even older/weaker search engines (yahoo, lycos, excite) don't return bitcointalk. WTF?!
Until know it's DuckDuckGo and Yandex returning it, and I'm not really comfortable with the thought of getting to use Yandex search.

If I understand that blog post correctly, google has updated their algo to return results that are relevant to the query being asked, rather than key words in a query. So searching for cars with the best safety rating might return a result that talks about a safety metric and ranks cars accordingly, but might not have the term "best" nor "safety" in the content of the page. 

In the past, when searching for something, you might encounter a webpage that has many random keywords unrelated to eachother, and no actual useful content. This change seems to be making it less likely these types of pages will be returned in search results.

Google always had the option to restrict the results to the ones from a certain period. And it was great, and it should do for your use case.
But if no proper results are found whatsoever, there's nothing to restrict...

Giving search results is not going to generate any profits for google. The ads next to the search results is what generates revenue for google. This means that relevant search results will generate more revenue for google as people use google more often to query information. Google wants to maximize the search results for people that answer the question they are asking.

Making a change to determine what is outdated and what isn’t is not expensive, but it is probably difficult.

What google is doing borderline evil and I guess that is why they removed clause ''don't be evil'' from their code few years ago.
I stopped using google for search and for emails, only thing I need it is for my youtube account, and I use all other alternative search engines that are privacy oriented  like DuckDuckGo, Qwant and Startpage.
Problem is that google holds nearly %90 of market shares for search engines and most people still use only google for searching anything on internet.
I tried searching several of my bitcointalk topics and I also couldn't find any results on google.


Yandex search is also showing similar results like DuckDuckGo, but it's obvious that google changed their algo code and I don't think it's only crypto or bitcointalk related but it is probably part of some bigger censorship plans.
Maybe this problem with google became much bigger in February of 2021 with their new manual censorship policy:
https://www.breitbart.com/tech/2021/02/09/google-quietly-escalates-manual-search-censorship/

I've noticed that without actually recognizing the implications of what Google's doing--if you search for pretty much anything, all you get are relatively recent results.  Not only that, the results are usually from mainstream websites that are probably employing a ton of SEO.  That's why I stopped using Google as a search engine some time ago, though I can't say DDG is ideal.

I haven't posted anything on bitcointalk so critical that I'd want it archived for decades, so this doesn't bother me so much--but there are tons of very helpful posts (especially in the technical sections) that really ought to be searchable on Google, and it sucks that they're basically being sucked down a memory hole.  That's Google for you, though.

That motto is waaaay outdated and they know it, too.

The great news is, privacy focused search engines such as Duck Duck Go are becoming much more usable than they were say, two years ago. Duck Duck Go is by far not perfect, but I've been using it as my primary search engine for well over 3 years. I've only ever had to resort to Google a few times, when a site specifically sends you through Google, or Duck Duck Go isn't yielding the search I need.

Although, I'm not quite sure why Google are not indexing older content correctly. I don't really understand the motives behind it. Newer information, doesn't mean its better than the old content. I'm guessing, as Google tries to serve the masses it will try, and provide relevant up to date information, as that's what users of their platform look for. This is probably especially important when concerning statistics. Although, I'd prefer to have them serve the entire history if possible, and just priorities newer content over old. 

If you tried doing SEO(search engine optimization) work for a certain blog or website, like damn you'd immediately realize how much of a headache it is to work with Google. After months and months of work you finally get your site to have decent traffic from Google search results, and the first thing you know a few months later, boom. Articles getting deranked. Google is notorious for changing things up with the algorithm A LOT, that could simply either effect your site in a good way, or sometimes even almost kill it in terms of traffic.