The update banner won't go away in Steam.

The workshop content update banner won’t finish and go away. Everything has downloaded yet it still says downloading even though its says 0 bytes remaining.

Try pausing & removing it? If that fails, reboot steam?

Restarted the computer and steam several times. Pause does nothing it acts like it goes away and instantly comes right back. If i try to download another game this keeps jumping to the top of the queue and making the other games take forever to download.

If you boot gmod itself, does it download any workshop addon? if no, the only solution I could think of is by unsubcribing to all, and resubscribing(note wich addons you had).

but i have over 300 addons and when i start gmod it downloads some addons but the banner sill wont go waway and something i noticed is the banner will duplicate and glitch in the downloads

Close steam for me. In your steam directory, you will see two files that I want you to delete, they are called ClientRegistry.blob and Steam.dll. When you next start steam, it will re-obtain or regenerate these files. This is the fix that steam support most frequently gives when errors arise from steam.

As a result of this, Steam may forget your login and require you to log in again and complete a steam guard verification.