well… you can’t completely avoid that, I’m afraid. As mentioned several times in this forum, an Arch system will never be a install-once-then-forget-about-it solution. Eventually, you will have to deal with *.pacnew files, the pacman cache and lots of other little things. You should definitely take a look at the Arch Wiki page on system maintenance, @cscs 's Maclean script, this video and maybe this one, too.
Also, if you are using BTRFS, you might want to deactivate CoW at least on /var/tmp/
sudo chattr +C /var/tmp