Can I re-encode h265 to h264 without quality loss?

I'm trying to re-encode mp4 video with h264 (probably, idk) from my webcam to h265 for video-size decreasing with ffmpeg ffmpeg -i idiots.mp4 -c:v libx265 -vtag hvc1 -c:a copy output-h265.mp4

Then I got a video with same video quality, but broken audio -- audio track lags behind the video.

Then I wanna re-encode video back to h264 for restoring playing quality and streaming video for a client, but receive same problems.

What am I doing wrong and are there other ways to get what I want, namely, to compress the video for storage and then decompress it before broadcasting to a client?

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