I see many Steam pages and social media posts with dithered posterized mess of GIFs. Most GIf encoders are terrible. GIFs could be encoded much better: gif.ski is designed to encode high-color video-like clips efficiently.
The next best option, a decade old WebP, is a mixed bag. In its best-compressing mode it will lower color resolution and add fringing like a JPEG. In its lossless mode it may be bigger than GIF.
If you have an option to use a proper video format, go for it. But often sites just allow upload of GIFs. If you send a newsletter you never know how primitive (Outlook) the client will be.