Yes I read that test from Jim Kasson on DPReview Sony full frame forum:
https://www.dpreview.com/forums/post/63099143
Also the high ISO tests show its a bit more noisy than the A7riii at higher ISOs.
Plus it has less dynamic range than the A7riii.
So for astro I see little reason to use it. it does not have any proper long exposure facility like Canon and a weak intervalometer that is only half featured.
16X pixel shift may be useful but mainly only in the fact that one click gets you 16 images so that would be a good stack. But again max exposure is 30 seconds.
Sony is simply not into providing astro type features.
Canon EOS R is ahead here in my opinion. The 30mp sensor is plenty sharp, is quite low noise (a tad noisier than the Sony) has accurate star colours and no funny RAW filtering. It also has long exposure ability longer than 30 seconds. It lacks an incamera intervalometer.
Variangle screen versus Sony tilt screen for me is no real gain as the variangle does not like L brackets. So it requires a special L bracket which are only now on the market.
EOS R touch screen is like a smartphone and nice to use. Sony does not have a proper touch screen only for autofocus point. So they are very behind there.
IBIS is not something you use in nightscapes.
Neither is dual card slots. Pixel shift (4 images) is workable with a tracker on the Sony's and is worth having.
Canon are rumoured to be releasing a high MP EOS RX later this year. Perhaps 83mp?
I imagine it will be somewhat noisy for nightscapes unless they have made some breakthroughs in their sensors which are good but old fashioned.
Greg.