That's about refunding.
The last tier can only be activated once you've used 10 earlier slots, so you can't refund 1-10 if you have mods active in the last column. The requirements not met means requirements to refund the slot.
If you refund the mods in the last column, the red writing goes away on 1-10
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Killapete232
Loading.... - vecchio
This explains it well ty