Some applications don't have icons on the taskbar, but just a standard icon.

General Help
1

There are no icons on the taskbar, just a standard icon instead.

2

Can you please clarify this or provide a screenshot? You might be referring to Symbolic icons, rather than Regular icons.
The way it reads: "There are no Icons, but standard icons" sounds self-contradicting on its surface.

3

If you are referring e.g. to web apps, this guide can help:

4

Can You post a Screenshot and name some Examples?