It looks like your GPG key for Yarn has expired. Can you try this command to reimport it?
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
It looks like your GPG key for Yarn has expired. Can you try this command to reimport it?
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -