I think it should be allowed in upload. Some think that's not a good idea because of possible include of javascript in SVG, or that the js part should be striped if present (better in my point of view). But in oher way, all already support SVG included in fonts for emoticon, that also allow this... That's sad to see this great open source format blocked due to this. I opened a bug in Mastodon to ask to include it there as regular file too.

SVG currently can't be uploaded, a server error.

If there is only attached svg, the following error is thrown:

Error: object must have a content

and if there is text in the post, with one SVG in attachement, the following error is thrown:

Internal Server Error

But SVG (including animated one, can still be included from another path, by markdown image tag. In this case, the animation is:

• fully displayed in microblog.pub
• a part is displayed in pleroma (it doesn't allow SVG uplaod either)
• Mostodon doesn't display it at all.

Here is an example with an animated SVG linked by markdown image tag : https://microblog.popolon.org/o/fec198ec47cd43dfa92909c68cc3dc77