I’m using the Remote Desktop client v10.3.5 on my iPad Pro running iPad OS 15.1.
I often use a messaging app in SlideOver mode. I noticed that if I have an active connection up in RD Client, and I slide out the Messages app, the RD Client will steal the keyboard focus and anything I type will end up going to the connected machine.
Steps to reproduce:
Open a connection in RD client.
Open the Messages app in SlideOver mode on top of the RD client window.
Click into a text box in the Messages app and attempt to type. Sometimes this will work, but if you wait a few seconds and attempt to type a few more characters, they will be sent to the RD client window instead of the Messages app.