Custom .ru domain serves truncated HTML (21KB instead of 106KB) — netlify.app works fine

My custom domain fitmost-bizdev.ru serves a truncated version of index.html
— the file is cut at ~21KB instead of the full 106KB.
The netlify.app subdomain bizdev-fitmost.netlify.app works correctly.

DNS config:

Site ID: 50f1fb0c-f513-4333-b7f4-5a759266cfcc
Site name: bizdev-fitmost

This appears to be a known issue with .ru domains on Netlify CDN edge nodes
(similar to this thread: Custom .ru domain stalls while downloading Next.js static assets, but netlify.app works)

Please check edge configuration for domain fitmost-bizdev.ru.