the other way of "burning" coins is what others pointed out which is by sending to an address that was created from a base58 instead of using a private key. it means you write any string using base58 characters then add its checksum.
Is it possible to know this type of addresses using block exporter so that I can know that the address is used for burning or not?
I mean, once I search for an address in block exporter, it appears to me that that address is intended for burning, or private key cannot be reached?
How do I know the addresses that were sent to OP_RETURN?
Is it possible to identify one of the keys in the multi-address?