Every article I've seen about Galleri mentions false positives as the main objection.

So I ran the numbers. For adults age >50 (the recommended group), standard cancer screening generates 33 false positives per cancer case detected. Standard screening + Galleri detects 236% more cancers with just 8% more false-positives for this age group.

The numbers would be slightly worse for a younger cohort, but still better than I'd have thought.