It might just be what @formerFP.Com.Manager has been posting here:
…
Together with our partners, we test the software before its release, and in some instances where a software update might result in some problems for users on a specific network or in a specific country, we prefer to delay the software release for that specific customer base and fix all the potential issues before making the software available to everyone.
That means that depending on your network provider, some Fairphone 3 users may receive this update later. Once the update is available you’ll receive a push notification to automatically update.
Possibly things didn’t work out with Scarlet, so you didn’t receive updates for good reason.