Where has my Germanic Ancestry Gone?

I have been looking at my Ancestry DNA results lately, and have been struck again by the unexpected disappearance of my German ethnicity estimate.

When I first received my DNA test results several years ago, my ethnicity estimate was 65% England, 22% Ireland and Scotland, 8% Germanic Europe, 2% Ghana, 2% Sweden and 1% Norway.

In 2019 an update to results showed small changes.  I was now showing 78% England, 10% Ireland and Scotland, 5% Sweden, 3% Germanic Europe, 2% Norway, 1% Mali and 1% Ghana.

My Germanic heritage has now disappeared completely.  In 2022, I seem to have swapped it for a totally unexpected 9% Norwegian heritage - to date I have exactly 0 Norwegian ancestors in my tree.  At the same time, 33% Scottish seems rather high for the one great great grandparent who is the basis of the only Scottish line in my ancestry, while my Irish great grandparent only shows 2%.  My English ancestry was always high, as my father's entire family comes from Essex and Suffolk for generations back, and my mother's family has significant English heritage as well, so I would probably expect a higher number than the 54% I have now.

The key is to remember that these numbers are estimates only.  DNA ethnicity is by no means an exact science.  These estimates are pretty good at the continental level, distinguishing between Europe, Asia and Africa, for example, in their estimates. Once they get below the continental level, to a regional or country level, all of them start to run into issues: country boundaries have changed; entire populations have moved; people from one area have invaded and intermarried with people from another.  All this makes accurate ethnicity estimates a challenge.  

This is all very well - but I would still love to know where my Germanic heritage has vanished to.  And why I suddenly seem to be part Viking.