it's not black and white like that. If you average 121% for 1 min you still do plenty of aerobic work.
It depends quite a bit on what quality you want to work out. Anaerobic power? Then I would simply go pretty much as hard as possible with using long rest periods. Something like 30s or 1min efforts with at least 5min inbetween. On the other hand, if you want to work out your hability to crank up some high power efforts repeatedly, then I would either work arround some 20s-1min efforts with shorter rests periods arround 1:1 or 1:2 work/rest ratio. The later would turn out being mostly aerobic work after a few repetitions while the former would draw more on your anaerobic glycolitic energy system, with long rests allowing for anaerobic energy system to restore itself partially at least.
It depends a lot on how you manipulate your variables and what's your goal. FOr exemple, I use a workout often described here: 2x4x30s/30s. I use it mostly during winter time and I average arround 175% of FTP for each 30s efforts, yet the overall workout remains mostly aerobic given the short rest durations.
There's a significant difference between going out and hitting some 30s at 150% of FTP or going out and hitting 4-5 x 30s at whatever you can sustain for that period, on a fatigue point of view.