Siri (and perhaps more specifically, iOS local voice playback functionality) is broken on two different iPhone 11 Pro with v14.5.1 (may have also been broken on the short-lived 14.5 version and just didn't notice). This bug can be noticed with Spoken Content, CarPlay, Siri dictation, etc.
It appears that Siri's function/actions are working correctly, as she successfully completes her various tasks, but it simply appears "broken" as she's unable to finish vocalizing her confirmation/action sentences on the iPhone. This can also be observed on other vocal Accessibility features where spoken dialog "cuts out" - iOS does appear to "silently" complete the spoken function.
Various iOS voodoo actions - to include deleting and re-downloading Siri (or other) voices, disabling/re-enabling Siri, and signing-out and back into Apple ID doesn't seem to improve this voice playback bug.
Siri was directed several times to ask Bixby for his help communicating - apparently, that doesn't work either! So aggravating, Siri's been turned off until the next version.
[Edited by Moderator]