Fix clear year and month field when converting to biblatex

CHANGELOG.md

@@ -54,6 +54,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 - We fixed an issue where JabRef switched to discrete graphics under macOS [#5935](https://github.com/JabRef/jabref/issues/5935)
 - We fixed an issue where the Preferences entry preview will be unexpected modified leads to Value too long exception [#6198](https://github.com/JabRef/jabref/issues/6198)
 - We fixed an issue where custom jstyles for Open/LibreOffice would only be valid if a layout line for the entry type `default` was at the end of the layout section [#6303](https://github.com/JabRef/jabref/issues/6303)
+- We fixed an issue where clear year and month field when converting to biblatex [#6224](https://github.com/JabRef/jabref/issues/6224)
 
 ### Removed
 

src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

@@ -39,6 +39,12 @@ public List<FieldChange> cleanup(BibEntry entry) {
                 entry.clearField(StandardField.YEAR).ifPresent(changes::add);
                 entry.clearField(StandardField.MONTH).ifPresent(changes::add);
             });
+        } else {
+            // If field date is filled it should be removed the year and month fields
+            entry.getFieldOrAlias(StandardField.DATE).ifPresent(newDate -> {
+                entry.clearField(StandardField.YEAR).ifPresent(changes::add);
+                entry.clearField(StandardField.MONTH).ifPresent(changes::add);
+            });
         }
         return changes;
     }