as @detlevhfischer also mention on twitter, esc key will not work on mobile / tablet (but I think some browser show a play / pause button on animated gif)

Last test I've done show that none of the major browsers currently stop gif anymore using esc key, Chrome and firefox allow it with a browser extension, no solution on edge or safari.

Agree... just had that issue with a client yesterday... have to install pause button for a gif.

@DavidMacDonald same problem here but will be hard to impose a pause button (specially for a animated gif) when I still have this technique listed as a possible solution

The technique has a test procedure, and if the browsers fail the test procedure
then people can’t rely on that technique. Note also that the technique does
not require hitting Esc to work - a browser preference or extension would be ok
also.

It may be that support is lacking in Edge and Safari and in mobile browsers so that the technique is effectively not able to be used, but we could easily add a note to raise the caution. I'm worried that this is a distraction from WCAG 2.1 work, so this isn't a very high priority.

@awkawk if what / how many browsers fail test procedure ? as wcag don't impose any browsers stack if it work on at least 1 browser they still can pretend to be conforming

@goetsu and they can do that even if the technique doesn't exist.

@awkawk no because it will fail 2.2.2 in that case or i'm missing something

Agree with @awkawk that it is not high priority - but a decision to retire this Technique seems easy if support is as bad as indicated.

A official technique doesn't need to be present to pass an SC.

@awkawk yes but a least if no technique say that using esc key is a possible solution they can't use it as a counter argument when someone ask for a pause button or other solution that can be used by real users

Following the discussion on Twitter I would like to add that a visible control would also be needed for voice recognition / activation (e.g. Dragon) users.

+1 for deletion

I came here to suggest clarifying that browser suppression of animation is a mechanism, which was the original intent of that term. Using an extension that stops animation should be a technique. I see that this issue wants to go in the opposite direction. As the author of the original text, I disagree.

In general, it seems that Chrome has all of its accessibility features as extensions. That should not prevent authors from relying on those features. Allowing users to globally set things in their operating system and browser is always better than requiring every website to do it. Each website will do it in a different way, which can add to confusion.

This technique dates to the time when people still remembered browsers that stopped animated GIFs when you pressed Esc. I'll quote Constructing Accessible Web Sites by Jim Thatcher et al (glasshaus, 2002; page 107):

The two major browsers (Microsoft Internet Explorer and Netscape Navigator) permit uses to stop animation in GIF's by pressing the escape key. Opera more effectively allows users to turn off animation by using the menu options File | Preferences, there in the Multimedia section uncheck the checkbox labeled "Enable Animation (GIF images)".

Internet Explorer 5 is no longer in use and Netscape Navigator was succeeded by Firefox. Cheah Chu Yeow's book Firefox Secrets (SitePoint, 2005) makes no mention of the escape key to stop animated GIFs. Page 241 points out that Chris Pederick's Web Developer Toolbar had a feature named "Disable Image Animations" (in its "Disable" menu), but this feature has long disappeared.

I am currently not aware of user agents that allow you to stop an animation by simply clicking a specific key or a keyboard combination. It usually requires installing browser extensions, client-side scripting or changing obscure settings in browsers. For Chrome, there is the extension GIF Blocker. In Firefox, you need to go to about:config, search image.animation_mode and set its value to "once" or "none". (See How does one turn off animated GIFs.)

@cyns wrote,

Using an extension that stops animation should be a technique.

Technologically adept users like us know about browser extensions and can install them. This is not true for the general population. And you aren't necessarily allowed to install browser extensions on computers in libraries etc.

@awkawk wrote,

It may be that support is lacking in Edge and Safari and in mobile browsers so that the technique is effectively not able to be used (...)

I would venture to say that support won't be added to modern browsers because too many ads on web pages rely on animated GIFs. (In fact, that may even be the reason why some browsers stopped supporting the ESC key to stop animations.)