The thing I keep hearing is that the show has a powerful 'the writer(s) had an idea they couldn't get made without an existing IP, but then upon getting a new show for the existing IP greenlit, they ignored everything about that IP that wouldn't let them run with their original idea' vibe to it.

Velma is not new Scooby-Doo content done with a fresh angle. Velma is whatever the showrunner really wanted to make, draped in bits and pieces of Scooby-Doo IP so the studio would think it would be interesting to the kids who watched Scooby-Doo who are now adults in the key demo. I'm sure sometimes this sort of thing works out fine. It looks like this isn't going to be one of those times.