ClipGrab depends on qt5-webengine-5.15.19-4, but building failed twice after many hours at the end, which is an extra pain in the …
The solution (for me) is a pre-build mentioned in the AUR comments
https://sourceforge.net/projects/fabiololix-os-archive/files/Packages/
Than install it via
sudo pacman -U
just in case if anybody faces that build error as I did.
Cheers.