That is really interesting.
In fact, according to the reports, Instagram has finally started limiting the number of hashtags some users can apply to their posts. Apparently, five is the total number of tags you can feature in a single update; some users get a limit pop-up when they add some hashtags within the IG composer so that it does not go beyond the post caption, and thus, it gets restricted.

Which makes some sense, because Meta has also capped the number of tags you can attach per post on Threads. In this case, the idea is that by capping tags at just one per post, that would reduce the capacity for spammers to target trending topics by adding as many popular tags as they can in the hopes of getting their updates into as many search streams as possible.

With this in mind, the same may be applied to Instagram as well, where spammers constantly flood popular tags, although one could also add more tags to the first comment that some users already do and which already generates more reach in some cases.

So, I am not sure if this would be effective or not, given there are ways to bypass it.

Maybe Instagram's also going to limit the discovery value of hashtags posted within comments, or comments (not replies) added by the creator. That would make this a bit of a bigger consideration if it were also enacted.

Either way, you should look at the proper hashtags that are for your business, and apply more specific tags to each of your updates. And five may be enough, but if it rolls out further than that, that could totally change the game on how you post and how you use tags inside posts.

Another possible indication is that limiting the use of tags could also be a sign that hashtags are not as valuable as they once were, especially since algorithms of social platforms are getting much better at sorting content based on a more comprehensive set of identifiers. If IG already knows what your post is likely about anyway, it probably doesn't need manual tags as much, which might be another process change.

We've asked Instagram for more detail on this test (and whether it's really just a glitch), and we'll update this post when/whether we hear back.

UPDATE (2/15): Instagram now says this was a glitch and isn't actually something it is currently working on.