Blaze Dying

I made a blaze farm, I´ve been testing different ways to prevent them from dying once a bunch of blaze gather in 1x1 block but it seems like there´s no way to do it, I´ve done this farm many times without this issue.

As you can see on the video, each time another blaze(s) come, the ones on the bottom die.
(I play it in survival but turned it to creative to record).

My apologies for the video fps.