It's because on ubuntu you have a simple and "free" choice in what language support to install - install more fonts (spend some disk space) to get better language support.
It is rational that you only need to spend resources on installing this, if you need it - you can save a few hundred megabytes, at least.
Maybe fonts-ancient-scripts is the one you need here.
My Firefox 81.0 in Kubuntu 20.04 tells me that the paragraph uses Noto Sans Egyptian Hieroglyphs Regular, DejaVu Serif, Noto Sans Cuneiform Regular, Noto Sans CJK SC, Twemoji Mozilla, and FreeSerif (in the same order as the fonts on the picture). All installed by default, I haven't tweaked anything.
For example stuff in this article doesn't render well for me (see the caption of the image): https://imgur.com/a/aFDSKyG