For context Peter Todd recently wrote a blog post with the following conclusion:
V3 transactions should not be be shipped at the moment. It has no compelling use-cases right now without ephemeral outputs, which should be discouraged, and in its current form is still vulnerable to transaction pinning.
Discussion about it is happening on the Bitcoin Core PR, and i think this thread is a more appropriate forum to discuss the merits of the v3 proposal at a high level.