No problems here after updating both my desktop and laptop to VP19 b648 - and clicking on the update option under the Help menu resulted in 'no updates available' or words to that effect. Just my experience.
I still have build 636 of VP 19 on one device (w/ 365 sub.) and the "New in update" lists Features and Fixes etc. of VEGAS 20 build 214. I wonder why it's mentioned as an "update" and not an "upgrade". After all it would be a new version which used to be regarded as an upgrade. Maybe the terminology is changing.
@vkmast, with the 365 subscription, you're always entitled to the newest version of VEGAS - whatever version that is. Therefore, with a 365 subscription, VEGAS Pro 20 is an "update" to VEGAS Pro 19.
For the perpetual owners, VEGAS Pro 20 is an "upgrade" to VEGAS Pro 19.
The way @jetdv describes it, it makes sense - but you're right, it is confusing, but it's due to the many different ways you can buy Vegas. I have not found a product yet where I would only have advantages and not find a disadvantage. Wait, ...........my wife of course 😁