Coinbase is to the bitcoin world what IRS is to the regular cash markets. They actually work with feds and steal money all the time from people that purchase citing their rights under KYC laws. All they have to do is say they think the funds were from or with intention of illegal activity or that they dont believe you are who you are. Money is then theres.
Now coins can be tracked and reused all the time and passed from one person to another. Alot of people have “dirty” coins bought from exchanges and there is nothing anyone can do it from it. Coinbase steals these coins from honest people and in turn sells them back into circulation to others and keeps the profits.
Most people dont know how many times this actually happens and when people expose them, they pay money to get them censored and alot of items scrubbed and deleted. If you dont agree with them, they silence you and get it hidden. The CEO of Coinbase Brian Armstrong has actually met with Reddit CEO Steve Huffman in attempts to get moderators and people removed that were against what coinbase was wanting.
You can still easily check online from people that have had their coins stolen and accounts locked on coinbase and also new accounts trying to push how coinbase is great to them and never any problems. I remember a time when daily people were jumping on r/bitcoin complaining of coinbase stealing their funds.
Coinjournal did a write up on this before and comments in regards to Coinbase trying to remove reddit posts against them are pretty common for years.