I don't know if it's still "a thing" but in the US and in the past if you took money out of your checking account so that PP couldn't take it without your consent, the banks would tap into your savings account to pay PP!
This is why you need to be very careful what bank US account you connect to PayPal. Because when you allow PayPal EFT access it comes with consequences from the bank, poorly defined ones.
I had a long conversation with my credit union and also with my wife's bank (for comparison).
If you have no money and PayPal tries to debit, even if you have no overdraft setup on any account most banks will still at their discretion decide whether to allow the EFT, put you into a negative balance and charge a NSF fee.
I have overdraft setup on my checking account and my CU said even though I had created a separate account with them just for PayPal (no overdraft) because I had overdraft enabled on my primary checking account it factored into whether they would allow an NSF EFT on the PayPal account with the NSF fee.
Neither one I spoke to was able to provide an actual written policy.
There are a few banks (online only it seems) that have an absolute policy that they will reject any EFT which would result in NSF without an NSF fee. I tested it and it worked as expected. I now use one of these as an intermediate to shuttle funds through. I'm on my second. The first got bought by a normal bank who imposed the above opaque rules so I had to find another.