Lazy loading - probably bug with delay option

At first I thought that delay option is what I need - make some threshold after that image is being loaded if still visible = image should be visible for defined time to be loaded.

Delay really pause loading/showing image, but (and I don't know if it is bug or not) lazy loading loads all images when smooth scrolling over flew - also images not visible for more then delay.

In this way delay option have probably no usage, because do not eliminate loading images not displayed for more then delay time. Loaded are always all images, only later. This cause another thing: when scrolling finished, all images are loaded at one time = a lot of requests can be send by client in one time.

Smooth scroll in long page by clicking in the section menu (which scroll long content byelement.scrollIntoView({block: "top", inline: "nearest", behavior: "smooth"}); ) shouldn't load all images which where flew over during smooth scrolling of long content and should load only images on the finish and respect delay time for this.

It looks like bug for me, because in current state delay option have probably no sense.