If I let the agent just produce some result it needed half an hour (or more) for, it’s very likely so convoluted that I can at best skim over it and then go „yeah yeah ok, it’s probably fine <merge>“.

I am seeing the first job ads for senior software developers which can debug the resulting mess. A lot of it will be just unmaintenable. They will get 20 years of technical debt with ten times the speed and ten times the volume.