Why is running while booted into snapshot dangerous?

Hi, I would like to use this script in my setup and maybe contribute if I have time. Now, in the README.md there is this dangerously sounding sentence:

One specific warning though there may be unintended consequences if snapper, or snapper_systemd_boot run while booted into a snapshot. BUYER BEWARE!

I don't understand how a script generating boot entries can do something dangerous. Could you elaborate on that?