Appreciate the replies everyone. @John47377 your response is really interesting. I see the error below after roughly 1000 seconds of running the SFSpeechRecognizer. Interestingly it fails at not the same exact time, which makes me think it could be a memory issue. I'm going to try a solution where I reinitialize the SFSpeechRecognizer proactively, say at 500 seconds, and accept a brief disruption in recognition.
[SFSpeechRecognitionTask handleSpeechRecognitionDidFailWithError:]_block_invoke Ignoring subsequent recongition error: Error Domain=kAFAssistantErrorDomain Code=1101 "(null)"
Error Domain=kAFAssistantErrorDomain Code=1107 "(null)"