Yes. Maria would notice her "lightning" transaction costs more than her friends who used a real lightning wallet because Maria's transactions are on-chain. She will especially care because so many people were suggested to use this wallet that Muun txs drop from the mempool (they use sent lightning payments without the necessary on chain confirmation) if muun does not raise the fee high enough to stay in the mempool. Eventually, poor Maria has to choose between paying really high fees, or waiting for things to calm down so she can transfer to a real lightning wallet, which she probably doesn't even know about because if the Bitcoiners, the people she deferred her knowledge to in regard to the best wallet software for her use case, told her about it, she would have been using that in the first place.