I have a A3 Umidigi smartphone, Android 9. I downloaded the images by Google Chrome (search images engine), and I can't find them in any folder (included Download, Pictures or DCIM), but I can see and use them as backgrounds (actually I use as background one of these downloaded, invisible images). I searched them using the App "Total Commander" (and other similar), and I connected the smartphone to the desktop by usb cable, but I couldn't find them. Google Chrome has access to the drive. Now, if I download another picture, Chrome asks me where to save it, but I have a dozen images I can't find.
Download folder (without the downloaded pictures).
/data/system/users/<User_Id>/
./data/system
is in the root folder. This is not the same as theAndroid/data
folder you access from your internal storage.