According to various reports, Instagram is now limiting the number of hashtags some users can add to their posts: five is the maximum number of tags you can include in a single post.
Instagram hashtag limit
Some users get a restriction pop-up when adding hashtags to an IG post, which prevents them from adding more than 5 hashtags.
This makes some sense, considering that Meta has also put limits on the number of tags you can add to a post in Threads.
The idea is that by limiting the number of tags, it will reduce the ability for spammers to target relevant topics (Instagram recognizes that hashtags are a good promotional tool?), adding as many popular tags as possible in hopes of increasing the reach of the post as much as possible.
Given the logic, the same could be extended to Instagram, where spammers regularly use popular tags, although you could also add more tags to the first comment, which is a common approach that many users already use and which in some cases provides greater reach.
So I'm not sure how effective this might be, given that there are ways around it.
Instagram is probably also going to limit the value of hashtags posted in comments.
Either way, you really should research hashtags that are appropriate for your business and apply more specific, targeted tags to each of your updates. And five will probably be more than enough, but if this is spread more widely, it could affect your publishing process and how you use tags in your posts.
Limiting the use of tags could also be another sign that hashtags just aren't as valuable as they used to be, as social platforms' algorithms are now getting better at sorting content based on a broader set of identifiers. If IG knows what your post is about anyway, it probably doesn't need manual tags, which could be another change.
UPDATE: Instagram now says this was a glitch and it is not actively investigating the issue at this time.