I have left the Netherlands (permanently) in 2014. However, I see that my BSN and DigiD are still available (I can login for instance to certain sites using DigiD). Is that a problem?
Your BSN and DigiD are personal. They remain valid if you leave the Netherlands. If you come back in the future you can use the DigiD again. However, if the DigiD has not been used at all for 3 years, it will be cancelled. You can keep using the DigiD to get certain personal information you need from the Dutch government, like info about our old age pension and tax obligations.
The validity of the BSN is indefinite. It will (in principle) remain yours for the rest of your life. Although we have been seen in individual cases that a BSN was granted to someone else (or even that 2 BSN‘s were given to the same person). But in principle the number will stay yours. If old age pension is paid out to you in the future the payment will be linked to your BSN. Als the 2014 tax refund will be linked to your BSN. That is why it is not deactivated or cancelled when you migrate from the Netherlands.