What does it mean when people you know or knew swipe yes on your dating profile?

Are they trying to express interest in you, or is it more like they’re just saying a quick; ‘Hi;’ to everyone they encounter, to whom they’re already acquainted? I’ve had two men I used to know swipe yes, but not send me a message.

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These were both men that I knew years ago and lost contact with, who told me to leave them alone, so I did. Then I mostly forgot about them until I saw them online.
What does it mean when people you know or knew swipe yes on your dating profile?
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