Hunch. The White House itself said on 26 August that the extra beef quota only applies for 90 days.
The 30 November extension market resolves on the presidential actions page of whitehouse.gov: YES if from 28 October to the end of 30 November 2026, Washington time, the president signs an act that moves the end of the extra lean beef trimmings quota past 30 November or gives a new amount of beef at the lower tariff after 30 November. The separate Argentina quota to 31 December does not count, and if whitehouse.gov does not open, Reuters and Al Jazeera reports settle it together.
We looked for cases where a US president eased limits on food imports for a fixed time, with the end date written in the act. We found seven such times from 1972 to 1981, mostly for meat and dried milk. Each time the president decided alone, and five of the seven were Richard Nixon.