In das Cloud Backup hochgeladen Fotos im NEF-Format werden nach längerer Zeit (etwa nach 2-3 Jahren) im Backup ins jpeg-Format gewandelt. Dann liegen die Fotos als Original im jpeg vor, obwohl sie im NEF vorliegen sollten

First of all, many thanks for your comments; they’re really helping me to deal with this problem.
Even via the web interface – both on the iPad and on the laptop – JPEG is always displayed in these cases. When downloading, too, only JPEG files with significantly reduced quality are available. The photos have obviously been converted in the cloud. Now I’m worried that all older photos will fall victim to this reduction in quality. In my opinion, this is a bug in the system. The question is also where to turn to at Adobe, as there is no direct support available.

I use the LR Mobile app on an iPad Pro and transfer photos directly from my Nikon Z9 to the LR app on the iPad using a USB-C cable. There, they are saved locally and then uploaded to the cloud backup. These are exclusively photos in NEF format. Once the upload is complete, if you open a photo in the app and tap the cloud icon, it shows that the photo is stored in the cloud backup as an “Original - NEF.” Editing in the app is always done on the original, which I retrieve from the cloud. The edits are then synced with the version in the cloud backup. Here, too, the cloud icon always indicates that the original in the cloud is in NEF format. This is my straightforward and simple workflow. Even if I want to view my photos after some time has passed, I open an image in the app, tap the cloud icon, and see the format in which the original is stored in the cloud backup. For all photos, this is always the NEF format. Now I have two folders of photos that I’ve viewed quite often, and the original NEF format is always displayed in the cloud backup. A while back, I revisited one of these folders, and suddenly, when I tapped the cloud icon for any photo, the original format shown was JPEG. Today, I noticed the same thing happening with another folder—once again, all the photos in the cloud backup are in JPEG format. After downloading these originals into the app, the JPEG format is also displayed under the Info button. So at some point, the format must have been changed from NEF to JPEG in the cloud backup without me having changed anything. One common factor is that this affects photos I took in 2023 and uploaded to the cloud. Attached are two screenshots: DSC_1839 shows the metadata of a recent photo that is correctly stored in the cloud backup in NEF format. The second screenshot, DSC_3915 shows an older photo whose format was unintentionally changed from NEF to JPEG. This is not a very plausible or understandable occurrence. My workflow is kept very simple—it’s always the same and always uses the NEF format. Now, suddenly, quite a few photos are only available as JPEGs in the cloud, which is very concerning.