Checked the last few pages and didn't see it mentioned, but I saw someone bring it up in another thread, so I know I'm not the only one.
On some browsers, the timestamps on posts will gradually be offset by an extra few minutes the longer you use the site. For example, a post that's supposed to read "a moment ago" will say 3 minutes ago, but every time you refresh it'll say "a moment ago" for a brief second before adding whatever the offset is. Use the site for a few more hours and it'll be offset by, say, 15 minutes per post instead of just 3, and leave it overnight and you'll come back to every post just reading the time instead of "x minutes ago" because the offset became long enough to instantly skip past relative timestamps. This also applies wherever else these timestamps appear, like in notifications or the reactions page. It didn't used to do this, only started a day or two ago. Closing the browser and then re-opening it completely resets it. Clearing the cache does not stop the behavior from reoccuring after continued use.
I've tested on 3 browsers, all on mobile (Android):
IronFox and Fennec both exhibit this behavior. They're both based on Firefox, with IronFox being a continuation of Mull (privacy hardening, disabling a few things to prevent fingerprinting, basically Librewolf's mobile equivalent) and Fennec being closer to vanilla Firefox but with proprietary code blobs and telemetry removed. I think I've heard of a few changes made in Mull/IronFox being sent back upstream to Fennec, but I don't 100% recall the nature of them. Not sure if this would be an issue with all Firefox-based browsers or just the schizo privacy forks, because sometimes these ones just have a bit of weird jank and fuck up things every other browser handles fine.
Brave could not replicate this at all even after using for hours, so it probably does not affect chromium-based browsers at all.
If anyone has experienced this on a desktop browser, or on "vanilla" Firefox, or on any non-Firefox browsers, please share. I'll try and find whoever I remember mentioning it and ask them what browser they use.