音声の再生時間について

I assume you did not do something like change the frame rate after loading the audio file. I wonder if you change the frame rate if it will time stretch audio files.

If you do not find a solution to the problem, does it happen during playback, in exported videos, or both?

Other things to check is the playback rate settings to make sure you are not playing/recording at something other than 1:1 (normal rate). You can make some adjustments there too I believe.

環境設定→オーディオハードウェア→バッファーサイズ（Mac)、レイテンシ（Win）の値を大きくしてみてください。