Breaking it down, it seems like a warrant expiration extension falls under the category of a Standalone Modification, meaning Gamestop would need to calculate the change in value based on something like Black-Scholes before and after the extension.
There'd be no impact to the income statement, but the balance sheet would see that change in value debited from retained earnings and credited to additional paid in capital, meaning net equity is unchanged.
The only thing anyone would actually care about is that the calculated change in value has the appearance of a deemed distribution, meaning it would be subtracted from net income for the purposes of calculating EPS for Q3.
tl;dr - There isn't an actual expense, but the calculated EPS number would look slightly worse for Q3 as a result. I think the only people that would be salty about that are the paperhands that already sold off their warrants.