It's the latter, irrelevant. All those FINRA daily short sale lists have done is confuse a lot of people. They have nothing to do with short interest.
Until a security is delivered, it is considered to be technically short.
If I sell some KATX today, it will show up as a short sale on FINRA records until my MM meets the buying MM "at the window".
This can take up to 10 days. All you are really looking at is the sell side volume minus any flips or buy side through the same dealer. For example. If I buy 1000 shares and you sell 2000 shares and we are both using NITE and this is the only volume they handled all day long, the system would show NITE is short 1000 shares until they deliver your stock to the buyer.
Stock is never delivered the same day you sell it. That would not be possible.
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