Disabling iCloud photos without losing full resolution photos

Hi there! I use iCloud photos, but since I want to make a backup of all my photos on my laptop, I have to disable iCloud photos. Now here’s my problem: every time I try to disable iCloud photos this message pops up. I just want to make sure if this won’t delete all these pictures (and will delete only the low res ones, so the normal ones will remain on my phone). I’m kinda really scared of losing these photos so that’s why I’m asking this here:)