Dimensions report as 0x0, thumbnails fail to load, and get this under the image icon:
Embed_test.svg (Invalid SVG file: Expected <svg> tag, got in NS )
php 7.1, php 7.2, php 7.3. Issue was not previously present before I updated the servers relatively recently.
current libxml versions: 2.9.8-6, 2.9.4+dfsg1-6.1ubuntu1.2
Setting $wgSVGMetadataCutoff to a frankly unreasonable number (4000000000) does seem to resolve the issue.
Example files: