This is a common problem with several vehicle models, not only Ford, while others have no issues at all. It is commonly blamed on Ford and Sync, which may be only half the issue. Apple has been known to have terrible issues with CarPlay. AA has had their fair share of problems.
Turning off noise cancellation on the iPhone has solved the issue for many. Also, if you have 2 iPhones plugged into Sync, the phones will ping-pong when waking and checking for mail, etc. This is Apple’s fault by allowing the phone to seize connections while plugged into a vehicle. Android figured this out…
It’s annoying but Sync isn’t really the only problem here, it’s also a known Waze bug…
You have probably searched this issue to death on the internet. From what I can gather, rolling back to 3.4.19101 fixes the issue for most folks, but does not for others, like the F250/350 owners. This points to other contributing factors outside of Sync, like phone, Bluetooth, or ACM settings, etc. In several F250 forum posts, changing values in the ACM fixed the issue for those owners. I do not know if anyone has success with this on a Ranger. 3.4.21194 is reported to fix the issue in the SuperDuty trucks.
Rolling back will not damage anything. You can always go back to the original or other versions of Sync 3.4. In fact, if you do not disable autoupdate (and possibly WIFI) the vehicle will request the update automatically.
You can use the Syn3 Updater on this site to perform the rollback to 3.4.19101.
Syn3 Updater - CyanLabs
Please read and follow the Documentation. Docs - CyanLabs Official Community.
I would suggest you go to the newest Sync build 3.4.21265 and see if that is better.