Photos cannot load adjustments. Please try again later.

Ventura and Sonoma support Canon EOS R50 Raw files.

Digital camera RAW formats supported by iOS 16, iPadOS 16, and macOS Ventura – Apple Support

Digital camera RAW formats supported by iOS 17, iPadOS 17, macOS Sonoma, and visionOS – Apple Support

Unfortunately, your 2015 MacBook Pro can't run either of those versions of macOS.

There is a possible workaround – short of abandoning Photos. I believe that the current version of the Adobe Digital Negative Converter would run on Monterey, and would support the Canon EOS R50.

Adobe – Cameras supported by Camera Raw

Adobe – Adobe Digital Negative Converter

If you used the free Adobe Digital Negative Converter to convert the Raw .CR3 files from the Canon EOS R50, Photos and other programs that use Monterey's Raw support libraries might be able to work with those .DNGs. You might have to play around with the settings in the Digital Negative Converter to figure out the most recent .DNG version that Monterey / Photos would accept. But hopefully there would be a conversion that would allow preserving most or all of the information in the original .CR3 Raw files.

Which particular Canon camera do you have? Is it one whose Raw format Monterey supports?

Many Raw files have the same file extension, but the format of a Raw file can vary from model to model even when you're talking about two cameras from the same camera manufacturer. An unsupported Raw file might look like an example of a corrupted Raw file of a known format.

Digital camera RAW formats supported by iOS 15, iPadOS 15, and macOS Monterey – Apple Support

I can't find any definite cure, but seems some corruption somewhere at sometime...

How to fix error "Photos cannot load adju… - Apple Community