Embedded fonts not used by default for rendering PDFs in Firefox

Steps to reproduce:

I have a PDF that I opened in both Firefox and Chromium browser on my Arch-based Linux Desktop running KDE Desktop Environment under Wayland.

The font rendering by default is a bit off on the Firefox side compared to that on Chromium. The Chromium one seems to be using the embedded PDF font, while the Firefox is not. I have checked the same PDF on external PDF readers on different OSs as well and the rendering done by the Chromium is the true representation of it.

Here are the screenshots of the rendered PDF:
PDF opened in Firefox - https://ibb.co/Fm6Q5mh
PDF opened in Chromium - https://ibb.co/t89q7xV

I checked the Font settings in Firefox and I never messed with it and they are the default settings.
Firefox font settings - https://ibb.co/y0CjVVj

System info - https://0.0g.gg/?234026138af5cbeb#GzwTR5d42k3o2Q5Tj16UsdM7GbBHaA9bjYA2zicaWw3D
Firefox about:support info - https://0.0g.gg/?96a9337b4bc24dee#12tJooqLEBKnmS8AtQTNU1qRRpuCGxDu867WxTqWboJm

Actual results:

Keeping this Font setting - “Allow pages to choose their own fonts, instead of your selections above” checked (the default behavior) should render the PDF without any modification with the original embedded fonts, but it does the reverse of it.

Unchecking this setting actually renders the PDF just like that of Chromium

PDF opened in Firefox with unchecking this setting - https://ibb.co/xJV1qL6

Expected results:

The ideal behavior should be that the PDF renders with the embedded fonts by default. The default setting in font section is also “Allow pages to choose their own fonts”. This should sync

I have also filed a bug on Mozilla’s Bugzilla, but there have been no comments there yet - https://bugzilla.mozilla.org/show_bug.cgi?id=1890332