The 2023-24 season is officially a consensus strong el nino, as Eric Webb has updated the Ensemble website, calling it a strong el nino: https://www.webberweather.com/ensemble-oceanic-nino-index.html
This is in agreement with NOAA: https://ggweather.com/enso/oni.htm
Strong/Super El Ninos since 1950
Super El Nino: 1972-73 (7 - considered Super by Ensemble, but Strong by NOAA), 1982-83 (8), 1997-98 (8), 2015-16 (8)
Strong El Nino: 1957-58 (6), 1965-66 (6), 1987-88 (6), 1991-92 (6), 2009-10 (5 - considered Strong by Ensemble, but Moderate by NOAA), 2023-24 (6)