Lazy loading not working

[UmerDSD]

I installed version [3.9.0.0 (2021050100)] on my moodle server (version 3.9.2).
The filter is on the top of filters list and is enabled to apply to both content and headings (I tried with content only as well).
The filter is using default settings, but the lazy loading is not working.

Whenever a page is loaded, all the images are downloaded irrespective of whether they are visible on the screen or not.