I believe I read somewhere that WhatsApp gets awoken by a silent notification with the cyphertext from the Notification Service, which it then needs to decrypt

I believe I read somewhere that WhatsApp gets awoken by a silent notification with the cyphertext from the Notification Service, which it then needs to decrypt before generating a local notification that actually gets displayed to the user. This was due to e2e, as/so the Notification Service can't have the plain text. Edit: as a possible explanation for the battery drain?