You can also permanently change your default to LE — acme.sh actually has instructions for doing so in their wiki.

I rather liked using ZeroSSL for a long time (perhaps just out of knee-jerk resistance to the “Just drink the Koolaid^W^W^Wuse Let’s Encrypt! C’mon man, everyone’s doing it!” nature of LE usage), but of late ZeroSSL has gotten so unreliable that I’ve rolled my eyes and started swapping things back to LE.