How can pushing large files or a large repository size lead to an 'http 400' error during 'git push'?

Many Git hosting providers or self-hosted Git servers (e.g., GitLab, GitHub Enterprise, Azure DevOps) have configured limits on the maximum size of a single push request, individual file sizes, or total repository size. When you attempt to push a commit containing very large files or an extensive history that collectively exceeds these server-side limits (e.g., `client_max_body_size` in Nginx), the server may reject the request with an HTTP 400 Bad Request because the payload is too large or malformed according to its rules, rather than a more specific '413 Payload Too Large'.