1.

Font size at 4k:  The font is just a tiny bit too small for my eyes.  I think most people would agree?

Here is an image to showcase the font size differences.  At 18px on 4k and 1 pixel down, it looks perfect even with the 'active tab' accent over it.  Also massively more readable.

Before / After

Would love to have the title bar font size made proper anytime soon!

2.

Tab Flickering:  It's not as big of an issue as the font size.  It is annoying, sure, and preferably please don't flicker when I click it.  But I assume this is not an easily solvable problem hence the second 'Extra Title Tabs' visual options.  That extra tab bar is just too much for me.  And it interferes with DisplayFusion's Window snapping options, shrinking the window little by little every time the snapping happens near the title bar.  But I choose Groupy over DisplayFusion.  That one is forever gone from my computer.  (Win10's monitor configuration etc is good enough and Window Tabs is much more productive than what DF offers)

Thank you for reading,

Keep up the great works you do, StarDock!