If it's a app, including fucking tik tok you bunch of morons, that was developed by a Chinese company all of the data on your device is going back to the CCP. It's just that fucking simple people.

Hmm...

I use AnySoftKeyboard instead of the default android keyboard or the Samsung keyboard just to preemptively avoid these kind of “issues” creeping up in the future.

Should I still be worried?

Is there a way to sandbox or scope the software keyboards to never see the network (wired ethernet, Wi-Fi, LTE, 5G or otherwise) on stock Android 13 ?

Other than:

Settings > Connections > Data Usage >

Allowed networks for apps > {app} > Wi-Fi only (and not use Wi-Fi) or Mobile data only (and not use Mobile data)

and

Mobile data usage > {app} > Allow background data usage > Disabled

Moreover, there is no "Network Permissions" setting option from what I can see even within Permission manager > Additional permissions.

So use Fcitx 5 Android instead. It's a open source IME application without requesting any permission except Notification, especially without network permission.

https://github.com/fcitx5-android/fcitx5-android