Microsoft updated something in backend which affects external images referred in SharePoint JSON formatting.
When you refer external images in JSON formatting, src in img element is changed to data-untrusted-src automatically, like:
You can fix this issue by adding external site domain from which you are using images in HTML Field Security settings -, detailed steps given at: Allow or restrict the ability to embed content on SharePoint pagesSharePoint Online: External Image URLs not working in JSON Formatting
I just tested this and it worked for me:
Similar thread: Hyperlink/Picture Column suddenly breaks external images in Gallery/Card Designer