Fix today
Your site's source code folder is downloadable
This is the exact wording EverThread uses when it finds this on a customer's site, written for someone who runs a business, not a server. The example site here is yourbakery.com.
What we saw
https://yourbakery.com/.git/HEAD is publicly readable. It can contain your whole code history, sometimes including passwords.
Why it matters
Attackers download it to find weaknesses and secrets at their leisure.
How to fix it
Ask your developer to block access to the .git folder today, then check the history for any secrets and change them.
For your developer
https://yourbakery.com/.git/HEAD is served publicly. Deny /.git/ at the web server, deploy without the repository metadata, and audit history for secrets.