Hello,
Thank you for contacting Rank Math support, and sorry for the unexpected delays and any inconvenience that might have been caused due to that.
I checked the website and I can’t seem to find any issue with your canonical tag.
Can you please share the specific affected URLs coming from your Google Search Console so we can take a closer look at them?
We are looking forward to helping you.
I find this error not in google search console, but in ahrefs.com while doing site audit, see screenshit below

Hello,
It seems that these URLs are actually images that don’t need to have a canonical. The Canonical was intended for content to avoid duplication and you don’t need to specify one for media.
Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.