Looking at the changes in price between a7R - a7R IV, and 5D III - R5, Canon have been charging a pretty significant premium compared to Sony for upgrading to a newer model. It's why I've skipped a generation and didn't bother with the 5D IV when the improvements didn't really seem worth the increased cost of my 5D III.
How much will Sony undercut them in the next year on an a7R V while potentially working out how to include the kinds of higher end 4K and maybe 8K video features in a way that makes them significantly more user friendly than what Canon have attempted here?
I feel a lot of people are missing the wider point with why so many are annoyed with the limitations on some of the R5's video features - they're not useful enough for those who are more interested in that side of the camera, while also driving up the overall price for those only interested in the other, better side! As much as it would be easier to think so, "the media" and every YouTube channel telling you bad news about this fun thing you want isn't necessarily some paid shill angling for controversial clicks.
Because people spend a good chunk of their savings on slightly compromised products?
Why do you think Sony can do any better for cheaper?
The main reason for the A7SIII being less prone to overheating is exactly that: 12 Megapixels on the sensor, less heat buildup on the sensor and much less data to process internally as well.
But with that megapixel count, it fits perfectly into those slightly compromised product category and no, I would not call it cheap by any means either...
Bump the A7IV to 4k60p with 10-bit codecs, and you will probably end up with a camera overheating in that mode, just like the R6 except it might not even do it in FF mode, but with the 1.5x APS-C crop instead, which is already an annoyance itself.
They always raise prices with every generation, they are really no different to Canon, except their product cycle is shorter and they have four separate FF mirrorless models running in parallel, so their tactics are different and the price increases might not be noticed as much.
The A7RIV isn't a whole lot cheaper and it misses completely on the video front and it uses an older Bionz X processor, it does not have the full touchscreen an new Menu, etc. is basically feels a generation behind Canon, it is an older, cheaper camera, so no surprise there. A newer one will be better but also more expensive, if they design an 8K sensor, it will be even more expensive.
Canon will address the more serious video shooter needs with different models (that RF-EF Speed Booster might give a clue about what they are planning...) Sony probably won't do it the same way, as their product line-up looks different, after the A7SIII the next step up is the FX9 video camera, and they will make a smaller version of that as well to sit in between those two models.
I really don't get all this comparisons when people should be looking at systems, not particular cameras (again, the bigger picture instead of the smaller picture).
