We say “secretly” because officially and publicly, Apple has yet to acknowledge the problem. Instead, the document is meant to be used internally and is directed towards Apple Authorized Service Providers. According to the document, it seems that Apple is letting them know that there will be customers who come in with this problem.
Apple has also told service providers that a potential temporary workaround would be to disable and reenable the personal hotspot feature, although how effective that is is unclear. We imagine that Apple will most likely have a fix for the problem, but when it is coming remains to be seen. If you were hoping that it might come in iOS 13.4, you might be disappointed as MacRumors notes that the latest GM release notes does not make any mention of this issue being fixed.
In the meantime if you are experiencing problems with your hotspot, then maybe try turning it off and back on again and see if that helps. If all else fails, we guess you’ll just have to wait for the fix to come via a software update.