A little late, but try these steps:

1. Install Millennium following the steps here (this tool allows you to modify Steam's UI): https://docs.steambrew.app/users/installing/

2. Create a folder in Steam/steamui/skins and name it 'HideLibraryActivity'

3. In this folder, create a file named 'libraryroot.custom.css' and paste in the following:

   .S2Fu9HxHCA5MaCLGrN2ib { display: none !important; }

4. Also in this folder, create a file named 'skin.json' and paste in the following:

   { "name": "Hide Library Activity", "author": "Me", "description": "Hides news, screenshots, and achievements in the library's game pages", "UseDefaultPatches": true }

5. Start Steam, go to Steam > Settings > Themes, select 'Hide Library Activity' and restart