Good day @Thanh
I’m sorry to hear you’ve run into this issue.
On one hand, please note that OKX has always traded wCFG (the wrapped version) and only approved the migration from legacy wCFG to the new CFG on November 3rd. You can read their announcement here: OKX to support CFG crypto migration | OKX
On the other hand, MEXC has always traded the new CFG. That means sending wCFG to MEXC was unfortunately a mistake.
To stay updated on the migration process, please make sure to double-check the token contract, exchange support, and the official migration post here: Centrifuge Token Migration Update - #2
Since OKX already supports a new CFG it would be better if you wil send your tokens to non-custodial wallet (Metamask, Rabby etc)
At this point, there’s nothing we can do from our side since the tokens are held by MEXC. I recommend reaching out to MEXC support directly for assistance.