In Principio and Ave Crux,
I am unable to understand what is being described nor what it is about; but I want to thank those who are working to find out what is going on.
God Bless you in finding out, and also praying that Saint Michael will lead you in this, and GOD'S Will be done.
PRAISE, HONOR, GLORY, and THANKS be to ALMIGHTY GOD FOREVER.

Since it appears all the upload images are .avif format, one last clue (then I'm done "sleuthing" - but since I haven't been on the site for awhile, maybe all these possibilities hae already been visited):
It could be a server setting, either intentional or just part of a server protocol update.
You could try using a file format converter to convert a file from .jpg/.jpeg format to .avif format before uploading.
AI:
QUESTION: Why would a website be able to upload a .avif file but not a .jpg/.jpeg file?
A website might allow AVIF uploads but block JPEG uploads because it's optimized for modern formats, offering superior compression (smaller files, faster loads) and better quality (HDR, wide color), with server-side conversions often turning JPEGs into AVIFs automatically for performance, though an upload block usually signals server-side rules or plugin settings forcing new images to the newer, more efficient format for better site speed and reduced hosting costs, notes Webmasters Stack Exchange, ShortPixel Blog and Alliance for Open Media.
Why AVIF is Preferred (and often forced):
Better Compression: AVIF files are significantly smaller than JPEGs at similar quality, leading to faster page loads, crucial for user experience and SEO.
Modern Features: Supports transparency, HDR (High Dynamic Range) for better colors, and wide color gamuts.
Performance Focus: Many website platforms (like WordPress) and builders automatically convert uploaded JPEGs to AVIF to leverage these benefits, improving Core Web Vitals. ]
Why JPEG Uploads Might Be Blocked (or converted):
Server-Side Optimization: The website's backend (e.g., a WordPress plugin or CMS setting) is configured to only accept or immediately convert incoming images to AVIF for efficiency.
File Size Limits: The server might have strict limits, and while JPEGs are common, AVIFs achieve those limits with less data.
Format Policy: The site owner or platform has decided to mandate AVIF as the standard, blocking older formats to maintain consistency and performance.
In essence: The site prioritizes speed and modern web standards, viewing JPEG as an outdated format that gets converted, or even blocked, in favor of the superior AVIF.

ANOTHER CLUE! It may be a royalty-free/rights issue. I saw another image posted on Gloria.tv with no trouble, and when I download the image I found that it was a .avif format, which is royalty-free, one-time purchase or unlimited license, etc. option.
When I changed the extension on the same image I posted before to .avif, it went through a preliminary upload process this time (which didn't happen before) then declined to post it since it wasn't a bonafide royalty-free image.
They must digitally watermark them.
PERHAPS it's a publishing rights issue. Perhaps Gloria.tv was getting in trouble for allowing people to post images people had no rights to and/or which are not public domain. I believe that may be the issue....possibly.
OR....Just a file size issue, as .avif files are much smaller.
AI:
AVIF (AV1 Image File Format) is a modern, open-source image format that offers superior compression, delivering higher quality images at significantly smaller file sizes than older formats like JPEG and PNG, making it ideal for the web by reducing bandwidth and improving load times. Built on the efficient AV1 video codec, it supports advanced features like transparency, High Dynamic Range (HDR), wide color gamut, and animation, all while being royalty-free, driving its adoption across major browsers and platforms.
Key Features and Benefits:
Superior Compression:
Files are often 50% smaller than JPEGs and 20-30% smaller than WebP for similar quality.
High Quality:
Supports 10- and 12-bit color depth, wide color gamuts, and HDR for exceptional visual fidelity.
Versatility:
Handles lossy and lossless compression, transparency (like PNG), and animations (like GIF).
Royalty-Free:
Developed by the Alliance for Open Media (AOMedia) with support from major tech companies (Google, Apple, Netflix, etc.), it's free to use.
Modern Web Standard:
Supported by all major web browsers (Chrome, Firefox, Safari) and operating systems (Android 12+, iOS 16+).
Why It's Used:
Web developers use AVIF to significantly speed up website loading, reduce data usage, and improve user experience without compromising image quality, making it the next step in image compression for the internet.