Now that I've seen what the AI/agents can do, those estimates definitely reek, and the frontend "senior" javascript dev's days are numbered. Especially for CRUD screens, which lets face it, make up most screens these days and should absolutely be churned out like in an assembly line instead of being delicate "hand crafted" precious works of art that allows 0.1x devs to waste our time because they are the only ones who supposedly know the ancient and arcane 'npm install, npm etc, npm angular component create" spells.
Look at the recent Tailwind team layoffs, they're definitely seeing the impact of this as are many team-leads and managers in most companies in our industry. Especially "javascript senior dev" heavy shops in the VC space, which many people are realizing they have an over-abundance of because those devs bullshitted entire teams and companies into thinking simple CRUD screens take weeks to develop. It was like a giant cartel, with them all padding and confirming the other "engineer's" estimates and essentially slow-devving their own screens to validate the ridiculous padding.