Greetings @hjf11060 ,
Thank you for posting on the Instructure Community!
This behavior is honestly very strange, I've personally never experienced anything like this before. Has this been occurring a lot when you read student discussions (like each time) or is it just on occasion? Also, are you by chance using the free for teacher canvas instance or does your school / institution have a paid account?
I feel the best thing you could do is hard reset the device your experiencing this on. However, if this is something that is happening on multiple devices and you truly think it's Canvas doing something, I recommend reaching out to support with your information so they can assist you.
Best,
Noah