Does the same thing occur in Latin American Spanish?
I don't think I heard vowel lowering in Venezuelan Spanish, because that's what you need to fully devoice lenited /b/. According to Wikipedia, it's not present in the whole Andalusia either:
Utterance-final /s/, /x/ and /θ/ (where ceceo or distinción occur) are usually aspirated (pronounced ) or deleted. In Eastern Andalusian dialects, including also Murcian Spanish, the previous vowel is also lowered.
What they're talking about is lowering vowels (pronouncing them "laxer", with the mouth more open) from their usual position: close /i/ /u/ to near-close [i̞] [u̞], mid /e/ /o/ ([e̞] [o̞]) to open-mid [ɛ] [ɔ], and open central /a/ ([ä]) to open front [a], so that these dialects have 10 phonetic vowels. Not phonemic, because they're analyzed as instances of /Vs/, where /V/ stands for any of 5 vowels of standard Spanish.
I heard only aspiration from Venezuelans. If I'm correct, then they would voice the aspirated /s/, because lenited /b/ is voiced too: [loɦ ˈβjexo]
And remember I'm talking about the Venezuelan variety. There's certainly more that aspirate /s/ in Latin American and Caribbean Spanish, Rioplatense dialect for example. But according to Wikipedia, it doesn't lower vowels in the /Vs/ context either:
In popular speech, the fricative /s/ has a tendency to become 'aspirated' before another consonant (the resulting sound depending on what the consonant is, although stating it is a voiceless glottal fricative, , would give a clear idea of the mechanism) or simply in all syllable-final positions in less educated speech. This change may be realized only at the word level or it may also cross word boundaries. That is, esto es lo mismo "this is the same" is pronounced something like [ˈe̞ʰto̞ ˈe̞ʰ lo̞ ˈmiʰmo̞] (there's probably an error here, since "mismo" in most dialects has a voiced fricative, so it should be transcribed [ˈmiʱmo] here), but in las águilas azules "the blue eagles", /s/ in las and águilas might remain [ s ] as no consonant follows: [las ˈaɣilas aˈsules], or become ; the pronunciation is largely an individual choice.[/S]
So there's even linking /s/ for some speakers. That's very interesting.
I suggest either writing to a phonetician who deals with Spanish, listening very carefully to YouTube videos or doing more research on Wikipedia. Either 3 will do, but if they're combined I think you'll learn everything you want to know about the subject.