Backlins Not Showing Up

[sconniswitch]

Hello Everyone, could you kindly help to undestand why i don't see backlink from certain sites. Can webmaster do something to hide backlink to crawler?I
I trade 10 backlinks on september 2021 but today i don't see them neither dofollow nor nofollow
Thanks friends

[datingbanking]

Sure:

https://moz.com/learn/seo/robotstxt

That's also how people hide some good old PBN links