Thank you very much for explenation. I was worried thinking someone stole it somehow.
Funny thing is that sender is slushpool so no way of contacting them.
I just took a closer look at the transaction...
That transaction is confirmed. It has more than 1200 confirmations!
This isn't a problem with the sender. Slush probably just included it in one of their own blocks, so they didn't need a very high fee.
This is a problem at Coinbase.
You need to contact Coinbase, send them the transaction ID and ask them why this fully confirmed transaction is still "pending" according to their website. They should have credited your account with the funds by now.