There are a few recent or upcoming changes that might take you by surprise:
If you refund a payment through PayPal, PayPal will no longer refund the fees you paid. In the past, if you refunded, say, $3.00, PayPal might take $2.75 out of your account and 25 cents from the fees you had paid PayPal (in other words, from PayPal's account). Now the entire $3.00 will be taken from your account, starting in May.
You are likely aware that Ebay made all fixed price listings "good til canceled," so you pay renewal fees on listings every 30 days. The solution is to switch to auctions (which still have set deadlines), or cancel the fixed price listings before the 30th day (without penalty).
Ebay has also been switching to its own "managed payments" service. They were coy about the costs, but now it turns out they will typically be 2.7% of the amount paid, which is cheaper than the PayPal rate of 35 cents plus around 3%. I have not enrolled for it yet, but apparently deposits go into your bank account immediately, rather than sitting in someone else's account (PayPal's) earning interest. Eventually all sellers will be forced to accept the new system, but that should be fine as long as it is cheaper.
The managed payments system will take credit cards, Apple pay, Google pay, and other payment systems. At first they did not include PayPal, but now they are linking to that system as well - which is good since Ebay users are accustomed to PayPal.
Finally, PayPal has switched its default settings. If you pay someone, the default is to consider it a merchandise sale and charge the recipient a fee. For a while it was presumed to be friends/family without a fee. My sisters got snagged on that new default setting last week.