In light of the newly documented risk, the Food and Drug Administration has updated the label of the vaccine to include a new warning: "Guillain-Barré Syndrome Reports of adverse events following use of the Janssen COVID-19 Vaccine under emergency use authorization suggest an increased risk of Guillain-Barré syndrome during the 42 days following vaccination."
https://www.npr.org/sections/coronavirus-live-updates/2021/07/12/1015366005/johnson-johnson-vaccine-is-linked-to-neurological-disorder-in-extremely-rare-cas
J&J Vaccine Gets Additional Warning on Bleeding Side Effect - The Food and Drug Administration said in a letter to the company on Tuesday that adverse-event reports suggested an increased risk of immune thrombocytopenia, or ITP, during the 42 days following vaccination. Symptoms include bruising or excessive or unusual bleeding, according to the agency.
https://www.bloomberg.com/news/articles/2022-01-11/j-j-vaccine-gets-additional-warning-on-bleeding-side-effect?leadSource=uverify%20wall
Same as with almost all other vaccines and viral infections. They pulled the JnJ covid vaccine after very few (out of more than 18 million people who got J&J, 60 cases of TTS were reported and nine people died. The analysis was based on suspected cases of TTS reported to the government’s Vaccine Adverse Event Reporting System (VAERS). The risk appears to be greatest—1 in 100,000—in women ages 30 to 49.)
JnJ was treated very differently from pfizer and moderna - fedgov had huge skin in the game with those two, so they weren’t about to put scary warnings on those vaxxes.