I think the more stressful part is the management expectation that things will speed up more, especially when you can generate plausible looking frontends relatively quickly. And if you have out of touch control-freak management without any technical experience, you waste more life time arguing with them.

Of course you also might exhaust yourself to some degree, as your own expectation might be that you can develop multiple things in parallel, while also having to review a lot of code where you might not have context, so in a way you have to hold more high level context in your brain state, what might be somewhat stressful. However, when you have been tech lead once, all of that is somewhat familiar.