my photo stream

That does not seem to be a widespread scenario given all the questions here about people losing their My Photo Stream and wanting to know how to get their photos back.

Do you find the service is still working for you by adding new photos to it when you take pictures? I suppose it is possible that the photos you are seeing are cached on the device and a restart would clear them. I can confirm that on my device My Photo Stream is no longer listed as an album in Photos and is no longer an option at Settings > [name on top] > iCloud > Photos to turn it on/off.

Apple stated that even when photo stream ended, you would not lose those photos. The photos in the photos stream would remain on the device on which the photos were taken. That is expected behavior.

If you took all of your photos on an iPhone and you had an iPad that had photo stream enabled, the photos taken with the phone would appear in the photo stream on the iPad. Unless the photos on the iPad were saved to the device before the end of photo stream, they would have disappeared on the iPad but would remain on the phone because that was the device that took the photos.

The text below is copied from this link.

Information about the My Photo Stream shutdown - Apple Support

The photos in My Photo Stream are already stored on at least one of your devices, so as long as you have the device with your originals, you won’t lose any photos as part of this process. If a photo you want isn't already in your library on a particular iPhone or iPad, make sure that you save it to your library on that device. Or, you can set up iCloud Photos.