Flameshot

Flameshot captures a screen region and opens an editing overlay right on top of it, so you can add arrows, boxes, text, highlights or blur before copying or saving the image. It can also be driven from the command line, and its appearance and shortcuts are configurable.

Flameshot is a cross-platform Qt application, and much of its documentation covers Linux desktops. For the Mac, the project publishes separate Apple silicon and Intel disk images on GitHub releases. Homebrew has disabled its cask because the build fails Gatekeeper checks, so expect to approve the app manually.