the.com/rubber stamp

means To approve something automatically and without real scrutiny, usually because the outcome was already decided elsewhere.

from From the literal rubber stamp — a carved rubber block inked and pressed to mark documents 'approved,' 'paid,' or 'received,' which caught on in offices in the 1800s as a fast way to process paperwork. By the early 1900s, 'rubber stamp' had stamped itself into the language as a noun and verb for any person or body (a board, a legislature, a committee) that approves things reflexively, lending its name to the idea of approval as mere mechanical motion rather than real judgment.