The text replacement feature of iOS (find it under Settings/General/Keyboards) is a useful tool to speed up typing, especially as a way to quickly post repetitive things like Instagram hashtags.
However, there’s a limit of 128 characters, and it’s not always easy to figure out how close you might be to that limit when you’re creating your text replacement shortcuts.
Here’s a great online tool that quickly checks anything that you cut and paste into it. I use it often.