[XT3 unxepected shutdown during photo shoot]

If after 2.5 hrs of shooting the battery is only used half-way, that is strange in the first place.

I always take a second body with me for shootings. Highly recommended. (And I'm not a pro.)

[XT4 Film great, stills washed out and blurred]

You can set the colors of your stills to your liking: Chose film simulation (example: vivid), chose contrast (example: highlights +1, shadows +1), chose color (+1??).

Question-Marks because I think that's not necessary. Probably "Someone" chose filmsimulation PRO Neg. Standard for you. Or "Advanced" and some weird setting is opted on your camera.