Well, it depends.
If what you mean is “148 is too low, all these builds should be able to do 150” OR what you mean is “148 is too high, all of these builds should only be able to do 140”, then that’s a separate issue, and I’m not really weighing in on that here. I’m just talking about what it would take for these other builds to come up to the current level of Zodiac Rend.
If, on the other hand, you mean “Only one person ever cleared 148 with Zodiac Rend, so that isn’t the norm!” then, well, I agree…
But the number of people reaching the top GR for any build is always going to be very small. You’ve already seen the GR levels I figure those builds can get to, but here are where they’re actually at, to the best of my knowledge:
Pro-Slam: 138 (Ulmaguest)
Fire Leap: 130 (Ulmaguest)
Phys Leap: 128 (A Korean player)
H90 Frenzy: 139 (Jedizinid)
Vile Charge: 135 (Darkpatator)
IK6 HOTA: 133 (Titannova)
R6 HOTA: 133 (A Korean player)
LON/LOD HOTA: ?
In each of these cases, too, it’s been just one person who’s cleared it, one time.