I guess Mr. Trevithick isn't a ship nerd. He took a section about the patrol ship's armament ("the Naiguatá has a 76mm main gun in a turret forward of the main superstructure, as well as a pair of 20mm cannons and two .50 caliber machine guns") almost straight from one of his sources (Infodidensa). Problem is, it's obviously wrong just from looking at the pictures and associated video. There's a 76mm forward, yes, but also a pretty prominent 35mm Millennium gun aft overlooking the helo deck. No sign of 20mm that I can find. The Navantia video he linked shows the weapons firing, which is a pretty good hint.
He's also confused about how commercial ship tonnage is measured. He talks about Resolute having "a gross tonnage of around 8,445 tons at the time." Gross tonnage is a measurement of a ship's enclosed volume; it doesn't change unless you start modifying the ship's structure. It's definitely not equal to the actual weight of the ship. Comparing to the patrol ship's displacement of 1720 tons full load is comparing apples and oranges,
Sorry for the pedantry. I'm bored today. I blame COVID.