I love flameshot, before it I used Shutter and I don't regret switching to Flameshot whatsoever. I use it on my work and personal laptops (Debian+xfce4)

Shutter is great in terms of features. I just recently discovered it.

But its code... Thousands (like definitely over 10k) of lines of procedural perl. I had a feature in mind I wanted to contribute and I couldn't even scratch the surface. I doubt this software can evolve any further.