According to
https://xcancel.com/argvee/status/1986194861855478213#m, google is a customer of fflabs.eu (
https://fflabs.eu) which is just such a "support contracts" arm. Certainly the fflabs.eu site claims at the bottom that Netflix, Google and Meta are all customers of theirs and the site also claims that their team is comprised of a number of ffmpeg contributors including the "lead maintainer" (
https://fflabs.eu/about/).
Additionally, a search of the git commits shows a regular stream of commits from `google.com` addresses. So as near as I can tell, Google does regularly contribute code to the project, they are a customer of the project maintainer's commercial support company (and that fact is on the support company's website) and they submit high quality bug reports for vulnerabilities. What are we mad about again?