iPhone App Thread Reply Issue?

I noticed a problem when replying to a thread, I took note of a username to mention in my reply & it was the first thing that I wrote so that I didn’t have to remember it. However once I go to the very start of the message (to type a message before the username needed mentioned), it just types over the initial writing rather than it moving to the right in line with what is being written (see attached photo). If I then delete everything that I have written, I then couldn’t delete the username at all.

Does that make sense? It’s difficult to explain.

Strange one. We’ll try to reproduce the issue.