SoulKeeper
Your English is great!
Yes, it seems to be that the behavior you're reporting can only be observed if there are different wallpapers for home and lock screens.
I have never noticed this myself because I have never had a wallpaper on my GOS Pixels (only black screen), so to be honest, I'm not sure how this behaved before the latest update. I only wanted to confirm that the behavior you observed exists on my devices IF there are two different wallpapers active.