Bold fonts fail to be rendered, default to normal in emacs 28

[Patrick Poitras <patrick.f.poitras@gmail.com>]

Hello all,

I am currently upgrading the emacs version for a container that me and some
people at work use for development purposes. The current container has an
emacs 26.3 version that is downloaded from Ubuntu's package archives. In
the spirit of progress, I am trying to get emacs 28 (compiled "manually")
working in the container to push it to everyone but am having some issues
with the font rendering.

When trying to render bold text, such as the name of the file in the tab
bar, or *in between asterisks* in org mode it defaults to (using C-u C-x =
to get the font used)

xft:-JB-JetBrains Mono-*-normal-normal-*-16-*-*-*-m-0-iso10646-1 for the
font to render.

In emacs 26 using identical configuration files (and identical system,
really), the same character is rendered using

xft:-JB-JetBrains Mono-bold-normal-normal-*-16-*-*-*-m-0-iso10646-1

I am seeking help in troubleshooting the issue, as I have reached the end
of what I am able to find about this. Please let me know if there are any
debugging steps I can do or any further information I can provide. I have
access to both sessions for comparison purposes.

I have tried alternative compilation options, adding --with-x --with-xft
--without-harfbuzz and -with-x-toolkit, without success. It used to use
another font renderer than xft at first, whose name now escapes me. (I
think it started with f and was roughly 6 characters long)

If this isn't the right place for this, please let me know and I will
redirect my questions.

Cheers,
Patrick