One thing that bugs me about this (and Tailwind) is the number of dependencies they pull in. Panda has 152 nodes (239, if you count their dev-dependencies)[0].
Tailwind has 98 (594 if you count their dev-dependencies).
I know they're only dev-dependencies, but still... I've got all of that code running on my machine, just to process CSS. I really don't love it.
How much do they care about simplicity, bloat, efficiency, security? The number of dependencies is a signal. Maybe not an important one, though.
As far as I can tell installing a package will also pull down all of its dev dependencies. This unfortunately leads to many typescript related annoyances such as jest typescript global types being pulled in despite not needing them.
I am not arguing for using sass, et al, but CSS preprocessors still have their place for those who wish to utilize them.