Even payments made from a balance can have the 21 day hold.
If you do not have that hold it is most likely a glitch and nothing more.
The 21 day hold is there for paypal's protection against any sort of issues arising with transaction involving newer members.
As per their ToS those limits 'can' be removed (but not necessarily so) when several minimum requirements/conditions are met including 90 days from the date of the first sale, at least 25 positive feedbacks and at least $250 in total sales received by the account.
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AGED SUPER HIGH LIMIT ACCOUNTS: 10,000/$1,000,000 and 25,000/$500,000