The aarch64 package is missing most of its contents (it seems to only contain PDF stuff, not the actual webengine shared libraries), breaking anything that uses it including parts of KDE/Konqueror. pkgrel 3 was fine.
I suspect a builder issue, since I don't see how that pkgrel bump could break anything. I am currently building the package locally to see if it fares better. Random guess: ran out of disk space or RAM while building?