My comment said nothing about 35mm lenses. Sensible use cases of 35mm lenses certainly make full field acutance a more important consideration for comparing 35mm lenses than sensible use cases of 135mm lenses make edge acutance a consideration when evaluating 135mm lenses.
Unless you want to be the best 135mm brick wall photographer in the world, I guess...
Perhaps my comment on the 35mm 1.4 Art should have been directed at one of the subsequent posts which mentioned (the real) focusing issues of the lens.
Anyways, my issue was specifically with your comment about people who cherish the Sigma 135mm 1.8 being uninformed and the lens producing nasty results. I am curious what justifies this strong lenses, as any comparision I have found so does not make it apparrent to my eyes what the issue with the Sigma lens is.
Here, the Canon is on the left, the sigma on the right. I don't see anything noteworthy about the transition.

Source:
https://jolsonweddings.com/education/sigma-135mm-art-lens-review
Here is a more complex scene, and while minor differences in the background blur's character, I fail to notice the nastines.

Source:
There don't seem to be that many direct comparisons between these lenses in particular, or at least I could not find them. So since you seem to have a much better source for detecting the differences that justify your choice of words, I would appreciate it if you could share that or at least point out what I am missing in the images above if they already demonstrate your issue with the Sigma lens.
The humble EF 85mm f/1.8 does better flat document reproduction work (i.e. test chart reproduction) than the EF 85mm f/1.2 L. It wipes the floor with the more expensive lens for that use case. But it doesn't produce near the same out of focus areas that the 85 L does.
The RF 85mm f/1.2L is sharper than the EF 85mm f/1.8 on the edges of the frame when imaging a flat test chart, yet still manages to render out of focus areas fairly nicely. But it still doesn't hold a candle to the older EF 85mm f/1.2 L II with how it renders out of focus backgrounds.
Same thing here.
This video contains a few side by side comparisons between Canons 85 mm 1.2 lenses and I don't see what is supposed to give the older lens an advantage.
SA control doesn't "give up sharpness to alter the bokeh". It uses apodization to smooth out-of-focus areas without any reduction in acutance of in focus areas.
I'm confused. The SA stands for spherical abberation control - I though apodization was a different mechanism. Am I wrong?
In any case, the SA slider does definitvely affect sharpness. Just look at the official trailer video:
Clearly the image is much sharper when the slider is set to 0, although the background is more fuzzy at the one extreme and more "bubble like" at the other. I thought you attributed the supposed degradation in background blur quality to excessive correction of spherical abberation and therefore this effect that Canon added to the RF 100 mm 2.8 macro was related to the topic. After all, Canon claims it is spherical abberation at play here (Further info on that, although in German:
https://www.canon-eos-r-forum.de/topic/36-rf-100mm-f28-l-macro-is-usm-mehr-infos-zu-sa-control/)