I can't tell if it's incompetence or malice, but this happened after the redesign. I think it's caused by the presence of recent posts from the "more posts" section.
Another consequence of the redesign, much worse than useless dates, is that you get completely useless results just because the same "related post" (the title of which Google happens to deem "relevant") appears over and over again at the bottom of different pages.
To get around this you can search for "site:old.reddit.com" or "site:i.reddit.com". One downside is you get fewer results.
Check out an alternate web client, like https://github.com/spikecodes/libreddit. Even compared to the old design it's much more lightweight and clean, and compared to the redesign it makes 1/4 as many HTTP requests, uses 1/20th the CPU, 1/4 the memory, and 1/2 the bandwidth, doesn't require an account to subscribe to subs, can work as pure static HTML, and doesn't track anything. I have poor Internet and the difference is night and day.
Yeah, what is up with that? It is unquestionably trash, and they simply aren't doing anything about it. The fact that they have an opt out means they acknowledge that a substantial number of users hate it.
Presumably plenty of people are fine with it and arewatching tons of ads and buying those absurd awards. I've been using old.Reddit and RiF app only forever, if that API goes so shall I.
yet from their point of view it probably improved the product -- how many viewers get suckered into watching an endless stream of content mixed in with ads.
I’ve noticed a similar thing with news articles. I’ll search $breakingNewsItem and see an article that was supposedly written yesterday, before the news was even news! Likewise I can search $ongoingNewsItem and click an article that Google says is “1 hour” (or sometimes even “10 minutes”!) old only to follow the link and see that it was actually published a week ago.
I assume this is reddit trying to game the recency metric.