Apparently there are calls for her recusal on the grounds that she held a critical stance before her current appointment. Which is an odd thing to ask for in my opinion, but I guess it's worth trying if you're on the losing end of this.
It's like the GOP currently trying to impeach a newly-elected judge in Wisconsin because she previously described the state's maps as gerrymandered, ergo she will not be able to rule fairly on the matter when it comes before the court. Obviously both examples are cynical and disingenuous, since the implication is that the only person qualified to do a job "fairly" is someone who has never thought about the relevant subject matter at any point in time.
They want to muddy the waters by arguing the FTC is impartial towards Amazon. But the problem with that argument is that it's not the job of the FTC to be impartial. Their mandate is to protect competition and consumers, which is naturally impartial to individual companies.