It seems curl https://install.meteor.com/ | sh no longer works for me (macOS 10.15.4, as well as the node:12.16.3 Docker image).
I get the following error: curl: (60) SSL certificate problem: certificate has expired
It seems like it’s related to the Sectigo root CA expiring:
Any ideas how to work around this to get Meteor installing?
At least a workaround for macOS 10.15.4:
I encountered the same issue today in conjunction with the codecov bash script. My quick fix: brew install curl and do what brew link curl suggest. You can check if you’ve picked the right curl with which curl (should point to /usr/local/opt/curl/bin/curl).
I have no time or patience to wait for 
to fix those things.