Flameshot is a really nice screenshot tool, but the big drawback is, that it only upload to Imgur, one of the worst Data hogs. The best and most complete is ShareX, there you can set the destinations to your like, but it has also a big drawback, it's Windows only (depends on NETframework, same as Greenshot)

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You can use Flameshot, but recomment to store the screenshots only locally and upload to share/host later to, eg vgy.me, or some self hosted one, like FileCoffee (valid for all type of files, image, video, multimedia, documents, presentations, etc.)