He kinda is, but he's also a pretty major regression candidate as the season goes along.
2021 (his current best season) was 144 IP of 67 ERA- | 73 FIP- which shook out to 4.6 rWAR | 4.0 fWAR. The quantity wasn't there, but the run suppression was supported up by the peripherals at 144 K%+ | 109 BB%+ | 71 HR9+
So far this year he is at 77 IP of 67 ERA- | 97 FIP-. The run prevention is still there, but the peripherals have backed up big time at 112 K%+ | 112 BB%+ | 100 HR9+.
The main thing saving Freddy so far this year is a redonculous strand rate. From 2022-24 he ran an 86 AVG+ | 105 LOB%+, so he was really hard to get a hit off of helping him run a better than average strand rate. This year he is limiting hits slightly more at an 84 AVG+, but the strand rate has exploded to a 119 LOB%+ that is likely unsustainable.
Love Freddy, and he has more than earned an extension, just not sure the Brewers should be paying any pitcher $20M plus for multiple years in their thirties.