No such thing I guess 'coz if there is, that exchanger is giving their service for free. Investors or users are the ones to shoulder transaction fees simply because they are jist using an exchanger platform. Transaction fees on my end is not a problem although in some instances the fees are too high. With regards to exchanges, Binance has one of the largest fees but I do still use it 'coz I'm confident with my funds on their platform. If you are hurting for an ezchanger fee then go with decentralized ones which would lower TX Fees.
If you see an exchange that claim to pay your transaction fees for you, you should avoid it. It will most probably be a scam exchange.
They can be either a scam exchange and try to gain more users before they run away with money by a scam exit.
Better, they don't run away with money but they will collapse by rotten management like FTX exchange. In 2020 or till 2021, FTX exchange waived out transaction fee on Ethereum blockchain for FTX users. Transaction fee on Ethereum blockchain was very expensive, $50 to $200 for one transaction in fomo times of DeFi 2.0, GameFi, Metaverse.
You can easily imagine how much money FTX wasted for their users.
It would be indeed suspiscious. The possible reason why they would do such thing is to gather as many users as possible and eventually collect their funds and leave with it in a sudden.