New Font is Unreadable
Text should be readable.
Font is so narrow as to be unreadable.

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{
"version": "0.58.3",
"success": true
}
Does this happen on the new UI too (e.g. on demo.rocket.chat)?
Yes.
(I presume this was a recent change because up until yesterday, our corporate version of rocket chat didn't have this font.)
@dbigham do you know if we fixed this problem?
Only thing I can think of that would cause this other than a custom font is someone having Roboto installed on their computers, and the font-weights mismatching... @dbigham do you happen to have Roboto installed?
Our current version is now:
{"version":"0.63.2","success":true}
... and the font is unchanged.
However, I noticed a message above asking me to check demo.rocket.chat. I apparently replied to that, but I'm wondering if I only saw the "new UI" part of that request and not the demo.rocket.chat part? Can't remember.
In any event, demo.rocket.chat's font is OK for me:

When I inspect, it shows the font family as:
-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen,Ubuntu,Cantarell,'Helvetica Neue','Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol','Meiryo UI',Arial,sans-serif
Meanwhile, our organization's rocket chat has:
-apple-system,BlinkMacSystemFont,Roboto,'Helvetica Neue',Arial,sans-serif,'Apple Color Emoji','Segoe UI','Segoe UI Emoji','Segoe UI Symbol','Meiryo UI'
I notice @vynmera 's message above asking whether I have Roboto installed. Not that I know of -- I don't know what Roboto is.
Some further experimentation: If I inspect the source in Chrome and start modifying the font-family by repeatedly removing fonts from the left side of the font-family list, it seems that "Roboto" is the font that it's using. That's the bad font.
Possibly related: For years now, I've been noticing more and more websites on the Internet using either that font or a similar font which is so thin as to be almost readable for me. It's super super annoying and I wonder to myself why the website's designers would do such an unintelligent thing. Possibly related? Is it some kind of configuration issue with my PC that is causing it to use a bad font?
Just uninstalled "Roboto" from my system, which appears to be a Google font. Presto. Rocket chat's font now looks beautiful, and I've also noticed that Google Chrome's settings are also no longer using that hideous font. Hallelujah! Thanks for the brilliant tip @vynmera !
Most helpful comment
Just uninstalled "Roboto" from my system, which appears to be a Google font. Presto. Rocket chat's font now looks beautiful, and I've also noticed that Google Chrome's settings are also no longer using that hideous font. Hallelujah! Thanks for the brilliant tip @vynmera !