The spots are pale and scattered, not the sharp, rusty or interveinal type you’d expect from a classic Cal or Mag deficiency.
It’s more of a soft yellowing – could be minor root stress, light substrate imbalance, or just early adjustment to soft tap water.
You can try a light CalMag dose as a precaution, but don’t treat it like a full-blown deficiency yet. Watch the new leaves – if they stay clean, you're in the clear.