I've been using the "standard" local Voice Assistant set up. Assist Microphone -> openWakeWord -> Whisper (stt.faster_whisper) -> the built-in basic intent system ("Natural Language Processing" conversation.home_assistant) -> Piper (tts.piper).
After upgrading from 2025.4.4 to 2025.5.0 whenever the Voice Assistant doesn't receive a command for a while (more than minute, less than hour), the first command/pipeline always consistently fails to speak the TTS. The audio cue for a response does play, but the TTS speech does not. I haven't found anything of note in the Piper logs or Voice Assistant debug. They all look as if everything worked.
On the second and subsequent commands the TTS speech does play. I'm not sure on the exact timing but after a couple minutes it is still working.
I tried downgrading to 2025.4.4 and this fixes the issue. Then I updated to 2025.5.0 and the issue is back. The issue also persists through 2025.5.1 and 2025.5.2.
EDIT: This is a single device running Home Assistant OS, with a USB microphone/speakerphone (hence Assist Microphone as the "satellite" although it runs on the same device).