I've been noticing that in several programs like Seafile, MKVToolNix, Manjaro Settings and KDEConnect (to name a few), the program is displaying in a strange font that is unreadable. I thought it might be a foreign language, but the only language I have installed is English. I have images below to show you what I mean. Is this a known bug? Is there any way to fix it? 
1 Answer
I managed to fix this issue. I don't know why, but when I installed google-fonts from the AUR, the text in all of my programs began to display normally. This issue is resolved, so this can be closed now.
locale -a