A purple text bubble on Instagram simply is the most commonly used theme in the chat. It does not indicate that you have been left on read, blocked or anything else.
How to change the purple text bubbles on Instagram?
If you don't like the purple bubbles you can change them to any other theme.
- Go to your Direct Messages
- Open the conversation you want to customize
- Tap the person name at the top
- Select Theme
- Go nuts on the customizations!
Available themes might vary depending on Instagram version.