How is $6000 per year (upfront) affordable? And that's the pricing for startups with <10 employees, surely large organisations / schools (which seem to be the audience of BigBlueButton) will pay much more. What about non-profits etc?

At this point tldraw v4 seems to offers no significant improvements over v3, which does everything I want from a whiteboard. I think most people who can live with the previous watermark will just stick with v3 permanently.

If you've got lets say a 6 person start up your wage bill would be ~$1 Million a year, $6000 feels quite reasonable. I agree that this seems pitched towards "we're making a saas" style startups and that for direct end users this is more difficult however if you can perswade tldraw to price this based on the IT staff your school has then if you've got a group of 5 schools each of 2000 kids, you probably have a IT team of 8-10, $500/month is $0.001c per child per day.