Broken images in most browsers using data-src instead of src in image tag

There are a lot of images in the handbook broken in most browsers showing <img data-src="..."> instead of <img src="..."> for the image in image tag:

A collection of pages upon which I stumbled with broken images:

• https://handbook.gitlab.com/handbook/values/
• https://handbook.gitlab.com/handbook/company/culture/all-remote/self-service/
• https://handbook.gitlab.com/handbook/security/security-assurance/governance/phishing/
• https://handbook.gitlab.com/handbook/company/culture/all-remote/

Checked browser which are not loading images due to <img data-src="..."> in html:

• Google Chrome
• Chromium
• Safari

Checked browser which are loading images and have <img src="..."> in image tag:

• Firefox

Browser not checked, but should be the same as Google Chrome/Chromium:

• Microsoft Edge

@marina.mosti seems to describe the same issue in #150 (closed)