If you look closely, Kana appears a little thicker than Kanji and Latin characters. Hangeul also appears thicker just like the Kana.
It seems to affect Dolphin and Strawberry. But I noticed that the Firefox file picker is fine:

Actually, Firefox itself is completely fine and I’m pretty sure it just uses Noto fonts as well. Fonts on Discord are also okay.
One thing I did notice is that “Noto Sans CJK” (JP/KR/SC/TC/etc) DOES appear thicker in the Font System Settings of KDE. This is what “Noto Sans Regular” looks like:

And this is what “Noto Sans CJK” looks like:

Notice that both “Regular” text do not appear to be the same. The CJK one is thicker.
Right now, a work-around is to set my main font as “Noto Sans CJK” but set it to “Light” instead of “Regular” and it looks pretty good:

But the Monospace Noto Sans CJK is thick as well with no option to make it lighter. Not as much of an issue as the graphical apps though:

This is a fresh install of Fedora 43 KDE btw. Hope someone can help me out here before I nuke this install for Bazzite, CachyOS, or something else lol


That’s not what I meant. You mention differences between dolphin (not ok) and Firefox (ok). So you need to check what they use as default fonts respectively. If there are differences you know what to do.
They’re both already using Noto Sans. IIRC Firefox has its own way of rendering fonts so it’s likely a KDE/Qt font rendering issue.
For all/relevant encodings?
Have you considered that maybe Noto developers made a choice there, to render Kanjoi thicker than Chinese characters? I know, that doesn’t explain why Dolphin would render them in a way that is more pleasing to you. Have you tried using other fonts altogether?