Your stack failed because the frames were not aligned accurately enough for stars. In astrophotography, alignment needs to be extremely precise across the whole sky, and Photoshop’s general auto-align can struggle—especially when the scene contains both moving stars and foreground trees that don’t move the same way.

A few likely issues:

• The stars shifted between frames due to Earth’s rotation.
• The trees/foreground may have confused the alignment.
• At 25 seconds, your individual frames already show some star trailing, so even a good stack may still show short trails.

For your current images, try software made for astro alignment, such as DeepSkyStacker, PixInsight, or Hugin. These tools detect stars directly and can align the sky more accurately; masking out the foreground can also help.

For future shoots:

• Use astro-specific stacking software rather than standard Photoshop alignment.
• Consider shorter exposures to reduce trailing in each frame.
• If possible, use a star tracker/mount to counter Earth’s rotation.
• If alignment software struggles, increase contrast temporarily so stars are easier to detect.

Also expect stacking to reveal vignetting or sensor dust more clearly, so calibration/correction may be needed.