Shared conditions can affect a group
Shrimp in one aquarium experience the same lighting, feeding, temperature, and water changes. Several molts close together may simply reflect animals reaching a growth stage under similar conditions.
The observation alone cannot establish that a water change or product caused the timing. Note when maintenance happened and compare with earlier logs.
Look for other signs
Check whether the shrimp are moving normally, feeding, and maintaining balance. A few empty shells with normal activity is different from repeated deaths or widespread distress.
Test water values that fit the situation, especially after a recent change or equipment problem. Avoid trying to stop a normal molt with an unmeasured additive.
Keep a useful record
Write down dates of molts, water readings, and maintenance. Over time, the record can reveal whether a pattern coincides with a routine event.
If multiple animals fail to molt or the colony declines, share the measurements and history with an experienced shrimp keeper or aquatic veterinarian. Timing is a clue, not a diagnosis.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.