It is not a premonition, it is a balance sheet
Sunday evening feels like fear of the week. Usually it is something else: the first quiet moment in days, with nothing to distract you.
In that quiet, what had no room during the week comes up. The week does not make the mood, the quiet makes it visible.
How to tell what it is about
If on Sunday you think of a particular person, it is about that person. If you think of a particular conversation, it is about the conversation.
If you think of nothing in particular and it is still heavy, it is usually about the direction, not the week.
What does not help
Filling Sunday up. That works as long as something is going on, and moves it to the evening.
And the question of whether you are grateful enough. It answers nothing and turns a feeling into a failing.
What you can do on Sunday
Write down what comes up. Not as analysis, as a list. Two minutes are enough. A lot loses weight as soon as it is on paper instead of circling in your head.
And look at the list again on Wednesday. What is still on it then is the real thing.
One observation
For most people Sunday evening did not get worse because the work got worse. It got worse because the week got fuller and it was the only quiet moment left.