Paul says, "As it has been written." That's a reference to Exodus 16--the story of the manna in the Wilderness.
In that story, God specifies that each person is to have precisely the same amount of daily bread: One omer, precisely, for each person. An omer is about a quart.
It then says that some people collected "much"--that would be more than one omer--and some collected "little"--that would be less than an omer.
But it says that when all the manna was measured out, each person got exactly one omer...no one got too much (more than one omer) and no one got too little (less than an omer).
So, with that reference as his foundation, Paul stated:
It is not that there may be relief for others and hardship for you, but it is a question of equality— at the present time your surplus is available for their need, so their abundance may also become available for our need, so there may be equality.
Equality. He says it twice, he doubles down to emphasize it, and then he underlines it with an OT verse that specifies a measured equal amount distributed to each person, no matter how much or how little each person personally collected.
And Paul is most certainly talking about money.