I do have settled the Pantheon Desktop for my MATE OS. I changed the color of the taskbar to black to have all the task icons visible (as they are white by default).
The time icon - in the other hand - is not visible anymore (because it's black by default), as you can see in my screenshot.
Is there any way to change the color of the time icon? How to change that?
I don't think many people here use the pantheon desktop so the odds to a solution on this forum are very slim.
Pantheon is the default desktop of Elementary OS, so your best chance to an answer is to ask your question on their community forum.
Their underlying OS is also Ubuntu (Ubuntu 20.04 LTS at the moment) so I don't think you will encounter any incompatibilities