Yeah, they did, but I think it was handled tactfully that did preserve Big Mum's status as an emperor. Big Mum is defeated, but it took everything they had (plus a giant explosion) to get the job done.
Oda cornered the Yankers so much is unbelievable. Before they told everyone to believe in Kaido's title and 1v1 superiority as an official narration box "confirmed" it. Alright I'll do that, but now Law and Kid being declared as winners doesn't mean that BM lost.
A defeat does not mean a loss. Example you can be defeat in battle and yet your country can still win the war.
Kidd and law are going to be out while bigmom isnt. Howevee they are declared winners not because they defeated her (knocked her out) but because they stopped her from going to the roof (which kidd explained chapters before that that's their new agenda)