Low Delivery Issue

[Rubioli]

Hey

I've set up my webpush application, and subscription and all works fine (mostly mobile) but when sending the delivery % is low.

For instance today I sent 5,105 and only 777 was received. What could be the issue?

Versions:

ruby '3.0.3'
gem 'rails', '~> 6.1.4', '>= 6.1.4.6'
gem 'webpush', '~> 1.1'

Any help is much appreciated!