In all cases except one, the feature seems to be working as intended:
> "After I sat for 15 minutes in the parking lots of two clinics south of San Francisco, Google deleted each from my location history within 24 hours. It did the same for my colleague’s two visits to clinics in Florida."
And in the one case where the author claims it hasn't been deleted, the screenshot [1] isn't showing Planned Parenthood as part of the timeline at all. It's simply showing it as a map location like other nearby locations not on the path (like "Himalayan Cuisine") -- and even labels it as "Recently viewed", which is why it might be prioritizing showing it when it might not otherwise. Not because it was in the timeline, but because it was recently viewed.
The only other criticism is:
> Often, Google kept my location on its timeline but only labeled it as the name of a neighborhood rather than a specific clinic. One time, it labeled my visit to a Planned Parenthood clinic as the coffee shop next door, and kept the record.
But what is Google supposed to do? It thinks you went to the coffee shop because location data isn't perfect. Sometimes it labels something adjacent and sometimes it doesn't label anything at all.
The feature seems to be working as intended, and if you want more privacy then just turn your timeline history off.
[1] https://www.washingtonpost.com/wp-apps/imrs.php?src=https://...