Concatenating in sync MP4 (H264+PCM instead of AAC) from a Sony 2018 Camera
In this case, I can think of two possible causes. First is differing timebases for the video stream, which is definitely the case here. And second is unequal lengths of video and audio within each file. Unknown but unlikely since these are files produced by a camera.

The reciprocal timebase for the video stream is reported as its tbn value.

For the five files, they are 25k, 24k, 24k, 24k and 24k respectively. The first one should be changed to 24k, else the videos streams of subsequent videos will be speeded up 4%, causing a desync.

Normally, I would just rewrap the MP4, only changing the timescale. However, since PCM isn't supported in MP4 - the workaround here is to rewrap to MKV individually and then concat. Matroska files have a fixed timescale of 1000, so a simple command will do.

ffmpeg -i file.mp4 -c copy -dn file.mkv