I don't think casual spectators give a lot of importance to everything Marvel. I only watched Eternals because it looked new and had an interesting story based on the synopsis. The others were just action movies: a spy movie, a martial arts movie, a Venom movie. Yeah. There's an audience for everything and everyone isn't obligated to watch everything Disney releases.
Disney is just making their money from the investments they bought. The criticisms of The Eternals movie weren't MCU related. They were mostly that there were a lot of characters and the pace of the roll out of the characters was meh. It's not a big deal.
What is Marvel fatigue and what are people afraid of exactly? That when their favorite character gets a movie no one will watch it and they'll think their character sucks? Remember that many countries closed movie theaters for over a year, so they all came out at once. Also, there's a lot of people who still don't feel comfortable with going to the cinema yet.