Vox had a good video on why dialog sounds terrible in movies/shows these days.

https://www.youtube.com/watch?v=VYJtb2YXae8

It boils down to a combination of:

- Actors speaking naturally instead of projecting toward a microphone

- Smaller microphones

- Dynamic range - big explosions have to sound loud, so dialog gets pushed quieter

- Downmixing from Atmos to 7.1, 5.1, stereo, mono

- TV speakers have gotten smaller and mounted on the back due to thinner TV's (and also poor quality speakers on devices)

I guess the solution is to buy a surround sound system and hope it's good enough.