When setting up gitea server behind a nginx reverse proxy, you might come to the problem when pushing files tracked in LFS that presents itself as a following error: HTTP/1.1 413 Request Entity Too Large The error itself does not specifically hint which component might be causing the trouble. Searching the internet proven to be fruitful, however the https://confluence.atlassian.com/jirakb/attaching-a-file-results-in-request-entity-too-large-320602682.html I have found seemed like it is not related to the problem.
Make sure that the size is greater than LFS_MAX_FILE_SIZE in your app.ini gitea config, if set to anything other than 0 (no limit). You can read more about gitea config in the https://docs.gitea.io/en-us/config-cheat-sheet/.