How to block specific notifications from an app?
If your Android is rooted and has Xposed Framework installed, then NotifyClean xposed module can be used to easily achieve the goal. I have mentioned its relevant usage here.

For non-rooted Android devices, I suggest you use MacroDroid or a similar app, such as Automate.

MacroDroid defines a set of trigger(s), action(s) and constraint(s) as a macro. You must enable Notification access permission and Usage Access permission in it.  

You would be needing the following macro.


Trigger:  Notification &rarr; Notification Received:


From: choose your app
Text Content: here's where you can play. Choose Contains or Matches to filter your text specific notification.

Action: 


Clear Notifications &rarr; Select Application(s) &rarr; select your app &rarr; provide the filtering details again

Constraints: none


Save the macro and you're good to go.

Note: MacroDroid can remove sticky/persistent notifications only in Android Oreo and above.