I'm sorry to hear about the unrecognized activity! There are a couple of things to do.
First, please contact PayPal customer support by phone. Click Help & Contact at the bottom of any PayPal page and then click Contact Customer Service, and Call us, and then either log in or click call as a guest to get the number. A representative can help determine if your bank account number was used or if your associated debit card was used. They can also get the unauthorized activity investigated and stop any additional fraud from happening on the PayPal platform with that instrument.
Once you find out which has been compromised, you should also contact the bank to get the number canceled and a new one issued. This will ensure that no further fraud can happen with that instrument outside of PayPal either.
I hope that this gets resolved quickly!
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