Google's transfer option from Play Music to YouTube Music went live recently. And a lot of people seem to be taking advantage of the feature, enough of them that the company had to warn users that the transfers are "delayed" because of "high demand." The transfer tool is available online and in the YouTube Music app. And at this point, transfers can take up to several days to complete.
The company didn't explain why the slowdown is happening. Despite this happening, more users are getting access to the feature. But we won't be surprised if even that is delayed, too.
Source: Android Police