I have a lot less green dots on my github calendar

I have a lot less green dots on my github calendar,
I do not know why.Who can help me?

Did you possibly remove an email address from your account, or delete a repository?

In general you can see possible reasons here: Why are my contributions not showing up on my profile? - GitHub Docs

I changed my default branch and then I changed it back,and that’s it.

Then there might be a caching issue. If it takes more than a few days to fix you could contact support and ask them to flush that cache.

I think you are fine, I’m counting it manually, it matches your timeline