On Windows 10 and 11, JetBrains Toolbox performs redraws that cause a full-screen blackouts both when it is opened from the System Tray and upon any mouse-over of any particular tool listed in the Toolbox (e.g. an installed Intellij IDEA or Pycharm icon).
Each blackout lasts several seconds and is consistent with full-screen resolution changes. It is present when operating nVidia Gsync-compatible (software-only) displays at 120hz or above. It does not recur when operating hardware Gsync displays. The total set of blackouts approaches seizure-inducing and lasts up to 20 seconds.