Hi @Olga_Dommes ,
I believe what you are experiencing are inbox reminders of tasks due 30 minutes before their due time, that looks something like this, right?
This is actually part of an A/B test that is running until 9th May which is when it will either stop, or persist, depending on the results. (I personally hope it stops! 
)
The switch that @Rashad_Issa rightly pointed to does not, unfortunately, affect these type of ‘reminder’ notifications.