Check that when you altered the part that you clicked “generate to last” before savng the alteration.

I find the red dimensions relate to features of the part that were after the alteration and only see them if I forget to generate to last

Here is an example, I created a drawing and dimensioned the 12mm hole and it came out black as it should, saved and closed the drawing.

I then opened the part and moved the slider up so it was above the last item which was the hole and saved the part.

Then opened the drawing and the hole is missing but the red dimension is still there.

Going back to the part and correctly generating to last will bring back the circle and make the dimension black. If I had deleted the extrude cut that formed the circle it would have gone from the drawing together with the dimension

Dimensioning from end to end is likely to be more robust than dimensioning the long edge of a rectangular block, if you might later add chamfers…