Error during file upload

Good afternoon. I have a broken file upload to the site. If you try to download a file of any weight (even less than 100 MB on a free tariff), it simply does not load. In the network debugger, I see that error 400 is returned, and it is returned by the Cloudflare web-server, with a description of bad request. I tried disabling all sorts of modifications, but it didn’t fix my problem. What should I do in this situation?

Does it work without Cloudflare?
If not, are you seeing Cloudflare in the response body?

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