This is about context. Giving and taking what, exactly? There is the possibility of one partner exploiting the other but to pin it to a ratio seems simplistic to me.

I would say depending on the circumstances one party will give more than the other but in average that has to swing both ways to get the right balance

I think there is mostly the dominant partner

My last relationship was more like a 70/10. You might say "that doesn't equal 100%". My reply is that's why the relationship is over.

I think that is fairly accurate. I believe you should always aim for the 50/50 but it can fluctuate and you should be flexible. In a nearly 30 marriage there were times I couldn't do my 50% and my husband picked up the slack until I was able to do my part. A few years later the reverse occurred. We can't always be on our A game and part of a partnership is picking up the slack when our partner needs it.

That was the financial settlement my second ex wanted, with her getting the 60%, even though we would have had nothing to settle if I hadn’t been putting money away. Final accord was pretty close to 55/45

I can't attest for "most" but for me those years were represented a 90,10 not healthy mix. Never again under those ratios.