All the available evidence seems to suggest that this is an accounting change, rather than a change in viewer behavior.
Though, Youtube has been like this well into the '10's, where some creators who had their entire channel shut down needed a twitter army just to provoke a response about what happened.
But if that's the case, why isn't YouTube coming out and saying it? Granted, it's not a great look to say "we've determined that our view counts are inflated because of $REASONS, so moving on from $DATE, we've applied a different methodology that will probably result in %xx loss in views." But the alternative of silence means that it's interpreted as "YouTube is screwing over the people they depend on for revenue because <fill in the blank>," which is at least as bad.