The under-invalidation happens because of the code in SVGImage::ServiceAnimations() (
https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/svg/graphics/svg_image.cc?rcl=beffe645c2e93de1f9090d73011080da9f0e06dd&l=647) which may cause invalidation of the animated objects while clears the repaint flags of the paint layers. In the next paint, PaintController finds that the animated object changed within a cached subsequence (whose repaint flags was cleared in SVGImage::ServiceAnimations()).

I would like to fix this but am not sure if I can get time before my vacation, so marking it Available for now.