[vednig]

You should probably have a sit down with TL and try to understand their perspective. And bring up questions you have while *not* sounding uninterested in new API spec.

Unless TL been recently promoted, they would know what they have to do to get better results, your deadlines might be extended if they're able to convince their superiors about the benefits of the new approach or drawbacks (enough) of the current one.

As previously stated TL has had a different role + goals than a dev, if you're still in limbo about the situation, you can still put the current work you did in your review cycle.