Sorry if this was addressed elsewhere, I didn’t see anything searching the forums. Not a big deal but after being a C5 user for over 12 years it just thanked me for my first post 
Old forum archive
https://archive.concretecms.org/community/forums/
Badges are carried over. You can check “my profile”.
The old community data exists, did you log-in using the same email address and password that you used in the old system?
Odd… yesterday it showed that I had only been active for a few hours (and gave me a little commendment for spending my first few minutes reading!) but today it looks like all is there.
I used the same email as the login suggested that we were doing email logins now only, but what’s odd is that the profile avatar and name were the same, but my history was gone.
ah, yes, that makes sense! I recall reading somewhere that when we log into the new site it triggers a migration of all our user data to the new site, which can take some time…
Yep - we got them all back after a day or two. @enlil alluded to some sort of mechanism that must have been it.