DEBUG see what the field thinks will show

src/Forms/SearchableDropdownTrait.php

@@ -139,7 +139,6 @@ trait SearchableDropdownTrait
                 return $emptyString;
             }
         }
-        $name = $this->getName();
         if ($this->getUseDynamicPlaceholder()) {
             if ($this->getIsSearchable()) {
                 if (!$this->getIsLazyLoaded()) {
@@ -598,6 +597,9 @@ trait SearchableDropdownTrait
         $field->setSource($this->sourceList);
         $field->setReadonly(true);
 
+        // Remove the text "Type to search..." on a read-only field
+        // $field->setPlaceholder('');
+
         return $field;
     }
 }

tests/php/Forms/SearchableDropdownTraitTest.php

@@ -73,6 +73,8 @@ class SearchableDropdownTraitTest extends SapphireTest
         $this->assertSame('My empty string', $field->getPlaceholder());
         $field->setPlaceholder('My placeholder');
         $this->assertSame('My placeholder', $field->getPlaceholder());
+        $readonlyField = $field->performReadonlyTransformation();
+        $this->assertSame('', $readonlyField->getPlaceholder());
     }
 
     public function testSeachContext(): void