If you’re tiny and no-one directly relies on your code except you yourself, especially if it’s all personal projects that don’t produce an income of any kind, a large CVS like GitHub is perfectly fine.
If you’re a large corporation whose size and visibility makes any shutdown a Very Big Problem for GitHub, you are insulated by sheer size and legal/economic threat.
But anyone in between? JFC, do honest risk assessments on something approaching a regular cadence. Figure out what happens to service users on a frequent basis, and start covering your arse against those risks.
In OP’s case, even something as simple as scripted backups to a destination outside of GitHub could have massively reduced all sorts of risks. While it would have taken some effort, a very recent backup could have allowed him to jump to something self-hosted (ForgeJo, etc.) over a day or three, letting him give a big middle finger to GitHub without having to wait most of a month.
Learn from other people’s mistakes. OP was very brave to provide this as a learning experience for everyone to benefit from -- don’t let it go to waste.