Mayfeld didn't acquit himself very well at all in Chapter Six, "The Prisoner", resorting to triple-wielding blaster pistols and going for More Dakka over accuracy, which led to fans mocking his marksmanship and past as an Imperial sharpshooter. Here, he proves to be an extremely competent sniper with a long rifle — but a sniper rifle is a poor choice for a job where one has to stay on the move through a cramped starship, which is why Mayfeld had to use weapons he's not as specialized in, and likely contributed to his lackluster shooting.
"The Believer" may seem like an odd title for an episode that centers around Din apparently going against his Mandalorian beliefs and removing his helmet in front of others to save Grogu. But Din's Mandalorian covert also places great importance in the protection of foundlings like Grogu — "The foundlings are the future." Din's ultimate Conflicting Loyalty wasn't about breaking his Mandalorian beliefs, it was about Din deciding which of his beliefs was most important: the concealment of his face or the protection of foundlings. And Din chose his foundling.
The so-called "pirates" attacking the rhydonium shipments en route to the Morak refinery make no attempt whatsoever to steal the rhydonium. Rather their goal is clearly to destroy it, meaning they are not pirates at all, but probably freedom fighters trying to get the Imperial Remnants off of the planet. And Din killed over a dozen of them.
The only comfort is that the rhydonium shipment gets blown up at the Morak refinery anyway, taking every Imperial there with it, by Din and Mayfeld once they realize why the Imperials are congratulating them for delivering it.
Not all of the people in the refinery were Stormtroopers. Some of the staff were clearly civilian workers. Which means that Mayfeld probably killed a few innocent people when he blew the facility.
