iCloud photo exports are losing their date?

I am trying to export my iCloud photos but some of them are losing their date and time information.

I am specifically exporting the unmodified originals and I understand that there is a difference between file properties and exif/iptc data.

I use the program 'Digikam' for my viewing my photo library. Most of my photos are correctly dated because Digikam can read their exif data. However, some photos are still being sorted by their export date.

For example, here is a photo which I saved from Discord on my iPhone dated 2022.06.18. When I export this as its 'unmodified original', it no longer has the date displayed on icloud.com. It actually has no EXIF, IPTC, or XMP data. So how does icloud.com know it's date, and why is it not exporting with this information?

My question is why does this photo lose it's date and time information when exported from icloud.com, and how can I export it in a way where it retains this information? Thank you.