[Need insight] blog on sub-directory or sub-domain

Hi, I have googled about this, but I could not see a clear winner.

When creating a product, or a service or a brand on the root domain, and I also want to have a blog going on where I can write about tutorials, guides or simply writing updates or news -

SEO-wise this blog should sit on the sub-directory or as a sub-domain?

And why?

Please enlighten me what matters as if 2022+