3 years later, is it sourdough?

In 2020 yeast was hard to get so I pinched off a bit of some dough and kept it going, a starter if you will, and have used it weekly ever since.

The yeast was a fresh cube that is the popular kind here in Sweden, not dried.

After having read quite a bit on the subject, I can still say I don't have a clear answer.  It would seem that the strain does change with time and accommodates its environment.  So I am guessing that the the strain I have now is substantially different than what I started with.

In case it matters, my usual baking method is to revive the starter a few days before bake from being in the refrigerator.  dough rest cool 12 hours or so.

I can get a very sour taste if I use a large portion starter or cool rest 24 hours.

So, what says the fine people of this forum, is this a "sourdough starter" or a hybrid pretending to be one.

is the potential Lactic acid,  glycemic index, etc. different as well because of starting its life as a factory based yeast?

Thanks in advanced.