"Total supply" is the first number everyone asks for. In RGB it is also the one number you cannot honestly print as a single value.
NIA — fixed supply. Genesis defines the issuance and secondary issuance is impossible, so initial supply is verifiable. Everything after genesis is ownership moving.
IFA — inflatable. There is an initial supply, a maximum defined by the schema, an issuance policy, and a history of every inflation and burn. Genesis only gives you the starting point. Read genesis, print "current total supply" — that is simply wrong.
Which leaves three numbers that routinely get collapsed into one:
max supply defined by the schema
initial supply verifiable at genesis
current supply only what has been disclosed, not what exists
Any listing that prints a single number is guessing.