The backpack resize is not work.
i can see the lines in the backpack i cannot use
or did i understood it wrong?

You only get as many rows as allowed by your permission.
It doesn't resize based on how many items you have, but it will recognize permission changes and resize based on that when the backpack is opened.

ahh so the grey lines at the bottom stay if i dont have permission to use them,

then i miss understood it.  it understood it that way that the grey lines will be removed if i dont have permissions^^ ^^

Assuming this is in response to the patch notes for the latest release, the problem being solved was that when a player is added to or removed from a group with permissions to different backpack capacity, the usable rows in the backpack wouldn't take effect for some time, meaning the additional rows they were entitled to would be disabled, or that they would have access to rows they no longer should.

now i get it ^^  thx