I am new to this and not sure if properly submitted. The latest flameshot 0.6 installed from solus software center does not install qt svg package - the result is missing button icons.
It probably needs this added to package.yml
rundeps : - qt5-svg
You can try doing this yourself by following the instructions here - https://solus-project.com/articles/packaging/
If you grab the repro
git clone https://dev.solus-project.com/source/flameshot.git
Commit the changes and submit the diff, someone will review it and if everything checks out the fix will be pushed out to the repo.