Are you in beta? I uploaded 10.1.8 with hide notification fix to beta channel. Let me know if it works.
Have you tried helper apps for other notifications?
https://www.xda-developers.com/hide-app-running-background-notification-android-oreo/
Thanks again.
I'm not in beta. I think I need a g+ account, but I don't have one. Could you post a link somewhere, so I could download it.
And the notification matter is more complicated for me. My problem is that I want only the big notifications absent. The small icon on the Taskbar is something I need. For instance if I suspend the gestures, I want to see the icon that the gestures are switched off. Another example is that I don't need the big Tasker or call recorder notifications, but I need to see their small icons in the task bar, so that I know they're running at all times. May be someone can create an app for that...
Also I'm still on nougat, not on Oreo.
The helper apps you provided a link to (thanks for that again) also provide solutions, but all of them eliminate both the big notification in the pulldown and the icon in the taskbar. So they're not going to work for me.
I repeat that I can live with the persistent notification, but they're getting too many and clutter the pulldown.
First let me say that this is intentional. At some point it looked like a good idea to allow for multi-finger gestures to work in a way where you hold all fingers still and do the gesture just with one finger. It mostly makes sense with starting zones and I'm not sure if anyone is really executing gestures this way

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As a quick fix you probably need to think of some different gesture that does not conflict with your regular device usage: 3 fingers, starting zone, more complex path. 2 finger gestures in general tend to conflict with zoom.
What you explained here is something which was discussed in this thread and I think it is a very good option. Actually I use this functionality all the time (holding one of the fingers and making the gesture with only the other one).
To give the other user an idea to possibly use as an alternative: My first gesture for recent apps is 2 fingers down anywhere. This one has never interfered with zoom for me. Also I have a second one which is DL/UR on the middle of the right border with one finger.
Alt+tab is only DL on the middle of the right border with one finger. And back is just Down on the middle of the right border with one finger. So these 3 gestures work pretty well for me as a close by gestures and similar movements.