Sign up to Github with Tuta mail is "Unusual activity", with just created Gmail it's fine

So I have a story to share:

I wanted to create a Github for my new project so I used my tuta mail for sign up. But I've got “We detected unusual activity”. So I followed the troubleshooting guide from Github:

• tried different browsers
• disabled plugins
• tried different networks
• tried different devices
• I even tried a different email from my local provider (Centrum email)

Nothing helped. And then I thought - I know what's your problem you assholes. You're bothered that I didn't use one of the mega-corporation emails like Gmail or Outlook, isn't it?

So in like 3 minutes I created a new Gmail account and voila - sign up worked.

And my question is - so an email created in like 3 minutes isn't an unusual activity Github? That's fine? But tuta for which you need to wait for 2 days for verification is a "Unusual activity"?

Rant over

PS. If you ask why Github, well, currently it's a small project for our community that might go nowhere eventually. I just need it fast, I need Github pages and I need it as accessible as possible so I don't demotivate people right from the start.