it happened to me too!
i got a new code and my friendslist had been reset. so i had to copy & paste all codes again.
but you can look into "Profiles" (tap on your avatar to open the Stats/Profiles screen). maybe both profiles will be there, and you could switch back to the old profile, and delete the new one.
i stumbled upon this too late. but i don't know if your old friendslist and code will be back again when switching to old profile.
my new code is JammaTal 4G68I3YY