To reproduce:
git clone https://github.com/ipanasenko/yarn-bug-demo
cd yarn-bug-demo
git cherry-pick origin/react-17
# fix conflicts ONLY in package.json, accept react ^18.0.0
yarn --mode=update-lockfile
git diff
You will see following diff:
Running simple yarn instead of yarn --mode=update-lockfile doesn't produce checksum: undefined field