Would be nice if in late 2023 Thunderbird was finally able to work with Windows DPI scaling.
I'm running 200% and everything is a jagged, blurry mess.
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I assume from that you are using the hidden preference suggested from years ago. Set that to 100% and try using the font size on the menu as that is the scalable way to make the changes for the last couple of years to prevent the jagged mess you describe.