### **Environment**:

Your OpenProject Version: 11.0.1 / Community Edition

Operating System / Browser / OpenProject language: Windows 10, Firefox 81, German

### **Steps to reproduce:**

1. Begin of the insertionChoose any other language than English (e.g. German)
2. End of the insertion Click on date picker of work package date (manually scheduled).
Begin of the insertion3.End of the insertion Begin of the deletion 2.End of the deletion Set an end date a couple of months after the start date, save.
Begin of the insertion4.End of the insertion Begin of the deletion 3.End of the deletion Click again on date picker (e.g., in order to modify the end date)

### **Actual Behavior**

When updating the date, the highlighting is still incorrect (similar to #34929 ): There are for some months, the highlighting is missing:

<figure Begin of the insertionclass="image op-uc-figure"><div class="op-uc-figure--content"><img class="op-uc-image" src="/api/v3/attachments/19576/content"></div></figure>End of the insertion Begin of the deletion class="image"><img src="/api/v3/attachments/19576/content"></figure>End of the deletion

### **Expected Behavior**

Highlighting is correctly shown for all months.