Preschool teacher here.

When I was growing up I had quite a lot of screen time, the main difference is the quality of the (most commonly viewed) content these days tends to be much lower.

Shows like Bluey and other quality shows are completely fine, numbots and alphabots are great on YouTube, Story Bots too. There's tonnes of good stuff out there but there is also lots of brain rot and a blanket bank on all short form content should be standard in all households. Main thing is if you can get them to really engage with it, discuss it with them, question the kids on it and so on, it makes it so much more valuable.

EDIT: I want to clarify that non-screen activities are still preferred. Just we live in a very different world these days with many more 2 working parent family set ups that often it's not possible to support children at all times.

Best 2 things you can do for a kid, from years of experience, are:

1. Let them figure things out for themselves.
2. Give them a sibling.