Self-Hosted Site: Create Post: "Something went wrong The response from the Jetpack site could not be verified."

Description

I am connected to my site hosted on a (LEMP Server) private domain via the Wordpress iOS app. When I try to publish a post on iOS, I get the following error message that pops up:

Something went wrong
The response from the Jetpack site could not be verified.
OK

I hit "OK" and it just returns me to the post edit screen.

What is going on here?
Why can't I publish a post on my Wordpress iOS app? Please help me debug this. Thanks.

Step-by-step reproduction instructions

Go to iOS app.
Select "My Site" .
Select "Posts".
Hit "+" icon.
Add a title
Write something
Hit "+' button
Select "Image"
Select "Take a Photo"
"Snap a photo with my camera"
Select "Use Photo"
Select "Publish"
Screen drops to Draft without publishing
Tap on "Arrow pointing in a half circle" icon, just above the "Failed to insert media. Tap for more info.".
Pop-up opens with the following message:

Media Options
cURL error 52: Empty reply from the server
Stop upload
Retry
Dismiss

I hit "Retry"
Blue Photo upload bar starts to fill up. Then it dissapears and gives me the screen that says:

Failed to insert media.
Tap for more info.

This cycle repeats itself.

Screenshots, screen recording, code snippet

No response

Environment info

Latest version of iOS and iOS App.
Wordpress Server = LEMP (Linux, Nginx, Mariadb, PHP8.3)

Please confirm that you have searched existing issues in the repo.

• Yes

No repository file, test, or entry point is identified in the report. Start by reproducing the iOS post-with-photo flow and inspect the server-side response associated with cURL error 52; done requires a reproducible failure and a narrowed cause for the failed media upload or verification.