The “intention” is to fix all known bugs. The “reality” is that Audacity is developed and supported by a small team of volunteers. Patches are welcome.
This is highly dependent on the Desktop Theme and version of GTK your distribution’s WxWidgets is built against.
Try changing your theme and see if it improves the appearance of those elements. I use the Mint-Y theme on Linux Mint and the only issue I have is that the dropdowns in the Device Toolbar display their text displaced downwards. I generally hide that toolbar so it’s not an issue.