Multiple U.S. politicians did in fact reimpose or newly impose significant COVID-related restrictions in late summer and fall 2021, explicitly tied to the Delta variant or related COVID developments:

• New York City: In early August 2021, Mayor Bill de Blasio announced that NYC would require proof of vaccination for workers and customers at indoor dining, gyms, and entertainment venues, with enforcement beginning in September 2021, and framed this as a response to rising cases and the Delta variant becoming dominant in the city. (en.wikipedia.org)
• Rhode Island: In August 2021, Governor Dan McKee’s administration mandated masks in all schools for the fall and Providence canceled its large PVDFest event scheduled for late September 2021, both explicitly in response to growing COVID-19 concerns “fueled by the Delta variant.” (en.wikipedia.org)
• Local mask mandates: Cities like Baltimore reinstated indoor mask mandates in August 2021, with officials citing the Delta variant as a “serious threat” to unvaccinated residents, reimposing restrictions that had been lifted earlier in 2021. (wmar2news.com) More broadly, jurisdictions such as Los Angeles County and others reintroduced indoor mask mandates and recommendations explicitly because of Delta’s spread and revised CDC guidance. (en.wikipedia.org)
• Federal level: On September 9, 2021, President Biden announced a new COVID-19 action plan built around combating the Delta variant, including broad vaccine mandates for federal workers, federal contractors, health-care facilities, and large private employers. These represented significant renewed federal restrictions tied directly to the Delta wave. (de.wikipedia.org)

While most of these measures stopped short of full March-2020-style stay‑at‑home orders, they are clearly renewed, substantial restrictions (vaccine mandates, indoor mask requirements, access limits for the unvaccinated, and event cancellations) imposed in late summer and fall 2021, with politicians explicitly invoking Delta and worsening COVID metrics. That matches the normalized prediction that some U.S. politicians would attempt to reimpose shutdowns or significant restrictions in fall 2021, citing the Delta variant as justification.