How to set the system tray icon monochrome?

[RokeJulianLockhart]

As #2479 (comment) states:

Currently, the icon is the undermentioned:

As ProtonMail/proton-bridge#475 (comment) explains, it would function a lot better in custom colour schemes. That's why AOSP mandates monochromatic icons for its status bar and new Material You application icons.

[RokeJulianLockhart]

As #2479 (comment) states:

gsettings set org.blueman.general symbolic-status-icons true