If you are a senior engineer then there is no need for you to be shipping code that you don't understand. People can definitely generate code a lot faster than before, but you also have a magic genie that can help you critique and improve the code that you're reviewing, including when that code was written by agents.
An experienced senior engineer with access to a coding agent is the most powerful code-understanding system that has ever existed. There's no excuse for shipping or approving anything you don't fully grok.
Time. The limit is time. With or without agents there’s an X number of lines of code my brain can digest per work day. But rate of production of code is effectively unlimited or heavily influenced by people who let go of at least some percentage of understanding. This forces the rest of the team to also let go to keep up. Without guardrails around the rate of code production, _teams_ tend toward 0% code understanding. Individuals working on solo projects or in tiny teams that can enforce social contracts are not affected.