Do you a FW version with December 2019 Security Update from Google (or later)?
In this security update there are changes to foreground notifications - they stay displayed for longer (after action is completed). This is not a bug, this is intended and this is part of Android 10 as of Dec. security update.
You may surpress the notification if you want, so that it doesnt show (swipe right slowly on the notification -> press the cog -> take your preferred action.