But nothing prevent them from tracking how you spend Bitcoin, threaten to close your account or freeze your coin.
PayPal have a history of freezing accounts which were being used to buy and sell bitcoin peer to peer, and they also have a history of freezing accounts which were buying bitcoin through PayPal's own mechanisms for a variety of unknown reasons. You can do a quick search on Reddit or even PayPal's own support forums to see dozens of users complaining of having their accounts arbitrarily locked, and having both their fiat and their bitcoin funds seized and inaccessible.
Obviously all those risks still exist, but now add on the fact that PayPal will be conducting blockchain analysis to see where your coins have come from and where they are going to. Not only will they seize your bitcoin like other centralized exchanges do, but they will also seize your fiat. A lot of people use PayPal (rightly or wrongly) for daily fiat transactions, sending money to friends and family, etc. If you regularly use PayPal for these things, you should think very hard about whether you want to use them to buy bitcoin, given how "shoot first, ask questions later" their approach is to locking accounts.