It is indeed strange, I am no less surprised than you, as it doesn’t make a logical sense.
In the meantime I’ve got some additional information regarding this and I was able to reproduce it by myself - maybe it will help to understand the issue.
In my Instagram I have the link to my domain that has the 301 configured.
When clicking it in the Instagram app (android confirmed, I don’t know how about iOS), I got the 522 inside the browser embedded in the Instagram app.
And by the all means I don’t understand it, as the browser used should not make a difference, unless there is something uncommon that Instagram does - but I still wouldn’t expect the 522 from Cloudflare, which is the case.
Here’s my profile to check it: https://www.instagram.com/diving.devops/
And the screenshot:
