The sibling explains well, although it's missing key detail. If you pay Musk $8/month, your replies to tweets will appear above those who do not. Just imagine how that might work here at HN, and multiply it by the "way worse actors" factor to get an idea of the result.

Since 'verification' is now just a paid service, it's also much harder to separate bad actors from good actors. There are other minor changes that have degraded the service, but it's difficult to tell if they're permanent or just another live experiment.