Daniel Owen's is saying that IGN's test is most likely an incorrect result since BO6 has to be restarted when settings are changed and the IGN reporter probably didn't do that and may have results from a lower setting. His 7900XT and 7900XTX are getting way lower averages at 4k Extreme settings
If what he says it true then I suspect the IGN results are for 4K Extreme with FSR upscaling so maybe someone can test a 7900XTX with FSR enabled and compare.
Also does Black Ops 6 really require you to restart for settings to take effect?