Unfortunately, on Ubuntu 22.04 or Linux Mint 21.3 (based on Ubuntu 22.04), I don't believe it is possible. See this in the Wiki:
Strawberry does not respect Qt style, KDE theme or icons on Linux.
Strawberry is built with Qt6, and needs qt6ct (Qt 6 Settings) installed in order to make changes to the theme (on Ubuntu based distros). The above distros ship with qt5ct (Qt 5 Settings), but that only works on Qt apps that were written with Qt5.
Qt6ct won't build on Ubuntu 22.04 because it lacks some dependencies, so we're out of luck for now. I think the next versions of Ubuntu (and Linux Mint) will have qt6ct in the repository.
I have set up a dedicated laptop just for music, with Linux Mint LMDE6 (based on Debian 12) which has a slightly newer package base, and does, indeed, include qt6ct. It worked well to achieve a dark mode, as well as certain fonts and icons that I desired.
I would love to be proved wrong about this, but I think we're just going to have to be patient -- as long as we are on the LTS versions of Ubuntu and Mint.
If anyone has had success compiling qt6ct on Ubuntu 22.04, please share how you did it!