This app was mentioned in 3 comments, with an average of 1.33 upvotes
If you happen to be on Android, you can download the GIF and open it in for example this GIF viewer to play it at a slower pace.
It's not perfect by any means, since it's still just very few frames, but you can make it out better...
Most file managers allow you to set a default app to play all files of the same type. And yes, Google Photos can be selected to handle all webm files if you so choose.
I would highly recommend giving Gif Player (or Omni Gif as it appears on your device) a try. Great interface with tons of useful settings & it handles webm files better than any other app I've found. For gifs it even has playback speed controls & can pause or go frame by frame. It can also play a few other video file types as well like mp4's. Oh, & no abusive permissions either.
There's an ad-free version if you're like me & can't stand ads in your apps, though the free one uses very noninvasive ads if you don't wanna spend the money.
One last thing: Chrome & Chromium based browsers handle webm playback very well & even allow for saving them to your device by long-pressing inside the video.
I'll point out that OmniGIF allows you to view GIF files frame by frame, although that's just part of what you want.