Nope, I have been running 5.x with this binding since (more or less) the first snapshot was released. 
Fyi, the binding stopped working for me and reported this error:
COMMUNICATION_ERROR
Error fetching data: General error communicating with service: no.seime.openhab.binding.panasoniccomfortcloud.internal.CommunicationException: New app version published - check the version number of your mobile app and enter the value as account config parameter (currently using 4.1.0), not retrying due to too many errors
I tried to add appVersion="4.3.0" to the bridge things config, because the Android app has that version - and now it works again 
Is that something that I have to do regularly?
Did you previously have a manually configured version number? If yes, then that version value is used as an override. If not, the automatic fetching of latest app version number might be broken.
Did you previously have a manually configured version number?
Nope. I followed the instructions and omitted it before.
Good. After checking my own logs, I see the same failure. Please try the latest version.