Yes, the SPL BURN instruction does decrease the total supply number stored in the Mint Account.
Here's how it works:
Token Account: This is an account that holds a specific amount of a particular token for a user. When tokens are burned from a Token Account, the balance of that account decreases by the number of tokens burned.
Mint Account: This is the account that represents the entire supply of a particular token. It keeps track of the total supply of the token in circulation.
When you use the SPL BURN instruction, two things happen simultaneously:
The balance of the Token Account from which the tokens are burned decreases.
The total supply of the token, as recorded in the Mint Account, also decreases by the same amount.
Therefore, the SPL BURN instruction effectively reduces both the individual user's token balance and the overall supply of the token in circulation, ensuring the total supply is accurately reflected after the burn operation.