App restarting instead of resuming
I am facing this issue on my OnePlus 6. Not only in my own app but also on other apps like telegram. Some times I try to resume telegram from task switcher and instead of just resuming, I see the share screen which came due to the last deeplink I opened the app from. Which means when I try to resume the app, the last intent is getting fired that was used to open the app. According to the following article this could be due to the launcher.
Ref: https://stackoverflow.com/questions/19545889/app-restarts-rather-than-resumes
As far as I know, that is how it is supposed to work. For some apps, the same thing happens on Google Now Launcher (Nexus 4), Quickstep (Essential PH-1), HTC Sense Launcher (HTC 10), Pixel Launcher (Pixel 3), and for Lean Launcher as well. These are launchers that I frequently use on my test devices.
For other apps, for example Play Store, it clears the launch intent, but most apps don't. Additionally, third party launchers does not have access to modify the taskswitcher behavior, not even on Pie. I'll try to see if I could do something about it, but I don't think so.