The lyrics window seems to have a hard coded max height which means it doesn't scale in size on large monitors and only occupies 1/2 the size available to it on a 4k monitor
Thank you for the report! I'm not quite sure if you mean the lyrics applet. If so, did you try to resize the lyrics applet in context view edit mode? (turn on context view edit mode, drag from the lower edge of the applet to resize) If this doesn't help, lyrics applet was actually updated/rewritten a bit in 3.1.1, could you try with 3.1.1? If it still doesn't work, could you provide a screenshot of the problem, please?
Assuming this is about lyrics context view applet and marking this as duplicate of a similar earlier report. It is resizeable, but the resizing is not quite discoverable enough yet (enable context view edit mode, drag from lower bar of an applet to resize). *** This bug has been marked as a duplicate of bug 487199 ***