I think that the frame rate (fps) of the project (Output Properties) is different from the frame rate that the video was shot (you can check the fps of the video in the Properties of the strip in the Source panel). Suppose, you have shot a video of 1 second at 24 fps and that your project timeline is set at 30 fps. If you drop this video in the timeline, the audio will last 1 second (or displayed as a green audio strip of 30 frames long). The video however has only 24 frames; so the blue video strip will stop at frame 24. Because these 24 frames are really 1 second of footage (and not 0.8 or 24/30 seconds as shown in the sequencer), the strip seems to be sped up.