I think the CDN url (in Discourse) should point to the same path as the root of your bucket.
Try changing s3 cdn url from https://cdn.kyrgyz.club to https://cdn.kyrgyz.club/file/kyrgyzclub-uploads-bucket (because the CNAME points cdn.kyrgyz.club to the backblaze domain, f002.backblazeb2.com, not to your specific bucket).
The file: https://f002.backblazeb2.com/file/kyrgyzclub-uploads-bucket/original/1X/df20411cc37e6e627202d7cdc4d2e5e3cb077701.jpeg
Can be accessed at: https://cdn.kyrgyz.club/file/kyrgyzclub-uploads-bucket/original/1X/df20411cc37e6e627202d7cdc4d2e5e3cb077701.jpeg