In my return to betta breeding this year after a few years absence, this is what I noticed.

A lot of betta nowadays seem weaker, more susceptible to disease and fin clamping, loss of appetite, etc.

Also, a lot of bettas nowadays seem much smaller when fully grown compared to just a number of years ago(referring to HMPK, HM, fancy coloured ones)

And also that a lot of bettas do not seem to be good bubblenest builders. I have only 4 out of 11 males that built good bubblenests.