I have been having this same issue over the past few weeks, but only when using my Macbook Pro on Sonoma. I've tried 14.1, 14.2 and now 14.3 and still no internet via Personal hotspot. I've tried my iMac which is not on Sonoma and that as no issues. I've tried my Sim in several other iPhones and the same problem with my Sonoma 14.2 Macbook Pro.
CREATE NEW NETWORK
I've tried the 'create a new network' approach on my Macbook Network settings and that worked for a couple of days but not since, even after trying the same method again.
DESPERATION - ANDROID
So out of desperation I purchased an Samsung Android phone to see if I could get that to work (I work on the road so Personal Hotspot usage isn't optional for me.. it is essential if I still want to earn a living).
SONOMA 14.3 & ANDROID TETHERING CONNECTION WORKED
I could not get the Samsung to connect properly to my Macbook Pro until I updated Sonoma to 14.3. Now using Sonoma 14.3 my Samsung Android (using the same Sim card from my iPhone) works perfectly 100% of the time.
The Samsung does not show as being a Personal Hotspot but rather as a Known Network.
SONOMA & iOS PERSONAL HOTSPOT ISSUES
So presumably the issue must relate to 'Personal Hotspots' communicating between Sonoma and iOS.
BYPASSING 'PERSONAL HOTSPOT' FOR INTERNET TETHERING
The Android work around bypasses the need for 'Personal Hotspot' functionality. iOS will not allow any mobile internet connection to be anything other than 'personal hotspot'.
Android operating systems appear to be more flexible and less restricting in this regard.
I'm 100% not a non-apple person... but needs must. The ONLY successful work-around at present is to NOT use an iPhone for tethering.
LOVE APPLE DEVICES BUT...
I love all my Apple devices but I need to be practical so I can work on the road. I am currently FORCED to use an Android phone to tether for internet access.
Hopefully at some point in the future (whenever that will be) this personal hotspot anomaly in Sonoma 14.3 on non-M2 Macbook devices will work.
PRE-M2-CHIP
Someone in this thread has said their M2-chip Macbook works without issue. So perhaps the issue lies in Sonoma not being backward compatible enough in older pre-June2022 devices.
Sorry if my currently working method is a bit sacrilegious... but it works for me currently as at Sat 3 Feb 2024.