After installing some plugins into WHM such as CSF or immunity the plugins category does not show up in WHM.
Sometimes, a server is created through an image and the /var/cpanel/apps is a file instead of a folder. You can test which one this is with the stat command:
# stat /var/cpanel/apps
Size: 118 Blocks: 0 IO Block: 4096 directory
Device: fd01h/64769d Inode: 56637347 Links: 2
Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2021-05-08 05:45:03.625810566 -0500
Modify: 2021-04-30 05:21:36.767498039 -0500
Change: 2021-04-30 05:21:36.767498039 -0500
If the output says "regular file" instead of "directory" then the apps file needs to be moved out to the way and replaced with a folder called apps instead. Once that is set then you will need to reinstall your plugins so that they can create the needed files in the /var/cpanel/apps directory.