I’m pretty sure manual would work fine as this only happens sometimes, but it’s very annoying. I’d say that 90% of the time it does exactly what A7RV would do, but the other 10% is an exposure juggling shit show.
Earlier I took a look at all the images I’ve taken in the last few weeks and every time it did this was when the subject was posed against a much brighter background (e.g. sky, sea). So I get that it’s a somewhat difficult situation for auto exposure, but A7RV would just transition between these changes much smoother.
It all looks like a firmware bug and that there’s a stray AE calculation that happens on full shutter press, but is never reflected on the monitor