My first significant Arch install was also pretty long-lived (not 10y but def >5)
Did you go straight to full-on systemd when you installed it? Arch was transitioning to systemd by default around the time of your initial installation (default since Oct 2012 so you would have just missed it if you went with defaults).
Mine was a few years of cruft-accumulation in already and my init system understanding was not super deep at this point so this (together with the glib thing around the same time) is the most disruptive upgrade breakage I recall. If it doesn't show up in your top 5 I'm guessing you dodged it?
I had a couple of storage/media servers on Arch that I set up in 2008. In 2012 when systemd came, I experienced lots of pain. I eventually got things working but it took me a long time not to hate systemd. They both failed within a few months of each other in 2018, putting them right around 10 years of Arch as well.
Did you go straight to full-on systemd when you installed it? Arch was transitioning to systemd by default around the time of your initial installation (default since Oct 2012 so you would have just missed it if you went with defaults).
Mine was a few years of cruft-accumulation in already and my init system understanding was not super deep at this point so this (together with the glib thing around the same time) is the most disruptive upgrade breakage I recall. If it doesn't show up in your top 5 I'm guessing you dodged it?