My tablet is running /e/os .
There the mail prog shows al the mail from my Gmail account and also all data from Google Calendar and Contacts
But in the Ecloud everything is empty.
The mail contact and calendar .
So the question is why does ecloud doesn’t show the things like the laptop

Can you try logging in to eCloud with your /e/ ID in the format and password and check if the contacts and emails are showing up there.
Also have you added your /e/ ID to your tablet …from Settings >> Accounts >> Add account