…and it is not ARC that has these requirements, it’s Roon 2.0.
You need to take manual action so you don’t get bugged to go back to the 2.0 in the future. The 1.8 stable branch will want to go to 2.0 on its own. 1.8 Legacy will not.
2.0 announcement had notices of minimum requirements changed:
our minimum requirements page also was updated in advance of the release:
You need your Mac to run 1.8 Legacy, not 1.8 stable. If you run stable, you will continue to have issues and annoyances.