How can he create this kind of backlinks without problems

So i was looking at competition backlinks (website a) and i noticed that there was this page (website b) that was creating alot of backlinks for this other website, and i found out that website b had a category that was just a link to website a so everytime website b posts something website a gets a backlink is this legit? How can both website do this without problems, it has been doing it since 2016

create your own version of website b or pay someone to do it

i wanted to do that. its smart. but it wont rank anything.

cons are that all your posts have the same backlink profile + these links are weak.

but is it blackhat? google can have problems with it?

They create syndication among backlinks.
But it doesn't bear much value.
I think instead of paying attention to this type of backlinks, search various guest post websites and give post there.
It worth value.