We don't use ProRes since some years anymore for highquality rendering, intermediate rendering or videomastering or archiving. Sometimes only if we need fast a reasonably video for presentation or beta master etc.
If you need a fast encoding time for some applications, it is ok or for some semi professionell productions with lower hardware equipment.
We made some test and the quality is not good in relationship to the size from the files and for professional works.
Here is a older comparsion with a difficult content, captured from a uncompressed source via HDMI and 1080P60@440Mbit/s Pro ResHQ and 1. Generation
https://s15.directupload.net/images/181219/k8zpltd8.jpg
You can see many blocking artefacts, if you zoom some levels in, banding and compression artefacts on the sky, in the trees, in the front of the street and so on. This looks like typical MotionJPEG singleframe compression codec and this on these high bitrate and only 1. Generation, this is not optimal for a master or for further re-compression or archiving.
Here are the next older example with a difficult content:
https://s15.directupload.net/images/181219/odd4uakj.jpg
Btw,the artefacts are not from the JPEG picture compression, its only with a 2:1 compression from the original bmp snapshot for upload here!
Little anecdote:
Disney was approx for 8-10 years ProRes "Fan" and made rescans and archiving their repository in Prores! Laters they notice this was not good enough and to bad for further mastering like HDR etc and they made fully new rescans again with lossless ACES singleframe@16bit archiving.