It might be helpful to understand the basic principles of making champagne.
After the first fermentation where wines are created or Vin Clairs, the process of blending occurs, and then the tirage is added, a mixture of sugar and yeast which kicks off the second fermentation crating the bubbles. The yeast dies/ or autolysis occurs, the dead yeasts release amino acids and also add depth anc complexity to a champagne depending how long the contact is.
After a certian amount of time the degorgement takes place where the dead yeast is removed and the dosage is added. The dosage is desribed in terms of extra brut, brut etc. Dosage is basically the additon of sugar.
What happens is the maillart effect, the sugars from the dosage react with the amino acids creating the yeasty, brioche, caramel aromas. This occurs over a period of 2 years post degorgement. In this phase the champagnes are often difficult to taste and best left alone, for this reason is the degorgement date so important.
A movement originating from the french gastronomy wanted lighter, less sweet champagnes which were not only ideal as apertifs but also could be paired with foods.Thus the emergence of extra brut and brut nature. The problem here if the dosage is too small meaning not enough sugar, it is unlikely that the maillart will occur and the champagne instead of developing the aromas you describe develops more like a wine.
This is in itself not a bad thing just one has to be aware when buying, what the dosage is, under 3 g/ls the dosage can occur but is not as pornounced as say with 6g/l.
Grower producers are in many cases obsessed wth terroir and believe dosage gets in the way of expressing terroir and thus they use no or extremely little sugar. Thes champagnes age different, more like wines, similair to white burgundy or pinot noir. The question here, is it better to drink when they are fresh or wait until they develop a patine of age, this is a matter of taste with no right or wrong answer,
To make things more complicated a lot of grower producers have perfected what I would call the oxidative manner of making champagnes. The wines are exposed to oxygen which speeds up the ripening process, they are held for the minimum amount of time on the lees and from the point of degorgement are ready to drink, little dosage is used. Agrapart is a good example of this sort of champagne. These champagnes can be drunk more or less direct after the degorgemnent, they also have aging potential but will d evelop more like wines than champagnes as high dosage.