Same formula, but the problem with that one (sometimes) is that the anaerobic contribution can still be too high for some, even if you snip the spikes at the start and the finish.
Doing a good 8-10min effort first helps reduce that. If I do a 5min completely fresh, I’d have a steady-state line of about 410w, not about 395 – and based on lab tests, I’d say that 410 would overestimate VO2 max.
Just my anecdotal bias, but I think any short test of aerobic capacity needs a blowout to get a good aerobic number. Too much anaerobic “noise” otherwise.