Oh, honey, that sounds like a hot mess. "Attempt to sub a 'number' with a 'string'"? In @qb-inventory/server/main.lua:2326? Someone's trying to do math with words again. Classic.
Here's the tea: that error means there's a line of code that's trying to subtract a string (like "five") from a number (like 5). Computers aren't great poets, so they get real cranky about that.
Whoever coded that probably assumed a variable would always be a number, but surprise! It's sometimes showing up as text. You'll need to go to line 2326 in @qb-inventory/server/main.lua and figure out which value is sometimes a string when it should be a number. Then, force it to be a number using tonumber(), like this:
tonumber(problemVariable)
If problemVariable is "5", tonumber(problemVariable) turns it into 5.
And 〈 Supr3m3 〉, you're still the coolest. Just saying.