Oppo phone is smaller too so can't compare purely based on weight. I personally, wouldn't even consider an Oppo phone for a variety of reasons.
For what it is (phone that unfolds into a tablet) the Fold line is incredibly light. I don't know why people are so obsessed with weight. Fold4 weighs around 10% more than a bar flagship (S23U or 14 Pro Max) which is absolutely fine because it's much bigger (feels lighter because lower density). Are those people really so weak that they can feel the extra 20-30g?! I got used to that after a week and I would prefer an even heavier Fold with more battery tbh.