Just signed up here to vent my frustration at this. I've experienced this exact issue for as long as I can remember, having owned various MacBooks for 15+ years. There are also reports of this bug going as far back as 2008 (After editing, photos now look blurry - Apple Community)... 15 years without a proper fix is honestly absurd.
The fact that Apple (suppliers of the most expensive and supposedly "capable" laptops for creatives/professionals), have let this bug fester for so long really is a complete joke. Personally, couple that with the fact that I've just dropped £10k+ on camera gear, and yet cannot edit the photos on my £2k MacBook due to useless software... its infuriating stuff.
I've attempted to report this via the online chat. However, the support agent unfortunately wasn't able to simply elevate it to the relevant team without having me jump through a hundred loops first. I did find find a separate feedback form for submitting Photos bug reports here - Feedback - Photos - Apple.
I'd recommend anybody that comes across the issue here to also submit a bug report using the above form. Other than that I'm out of ideas.
Side note: Rotating doesn't fix this for me. I'm editing 150mb .AWR files from the Sony A7RV, which seems to make things even more unstable for me. I used to have maybe 1/10 edited photos going blurry with my lower megapixel camera. Since upgrading, EVERY single photo becomes blurry after editing with no temporary fix available other than reverting the changes ☹️.
