Currently, PowerApps Launching Function is redirecting another app/page to different tab instead of same page. This feature is good for few schenarios but also we should have capabilities to launch in same page with using specific parameter value like (True/False).
Tipical observation on Launching function::
When I am loading page and clcking button where Launch Function is specified to load another app, it is loading successfully in different tab. But while I am reverting back from 2nd app to parent app with same Launch function with passing parent page web link url then it is loading in Same Tab. When I reach parent page and repeat the same steps, it is working in same tab.
Note: in my observation, Launching different tab only in first time execution of each session. Not sure the reason but observed.
I'm pleased to announce that screen targeting support (including "self") is now available in the Preview region and those on the Frequent refresh cadence in some regions. It is rolling out further over the next few days. You can tell if you have it if LaunchTarget is an available enumeration in your app: