Allow tooltip to return undefined

 tooltip: >
    [[[
        var show_buttoncard_tooltips= states['var.show_buttoncard_tooltips'].state;
        if (show_buttoncard_tooltips != "True")
          return undefined;
In order to prevent tooltips from showing you can return undefined like above.

.vscode/bookmarks.json

@@ -1,25 +1,5 @@
 {
 	"files": [
-		{
-			"path": "dist/button-card.js",
-			"bookmarks": [
-				{
-					"line": 3841,
-					"column": 12,
-					"label": ""
-				},
-				{
-					"line": 3843,
-					"column": 20,
-					"label": ""
-				},
-				{
-					"line": 3926,
-					"column": 26,
-					"label": ""
-				}
-			]
-		},
 		{
 			"path": "src/button-card.ts",
 			"bookmarks": [
@@ -29,12 +9,12 @@
 					"label": ""
 				},
 				{
-					"line": 1013,
+					"line": 1015,
 					"column": 40,
 					"label": ""
 				},
 				{
-					"line": 1103,
+					"line": 1105,
 					"column": 47,
 					"label": ""
 				}

src/button-card.ts

@@ -980,6 +980,7 @@ class ButtonCard extends LitElement {
           </style>
         `
       : html``;
+    let tooltipValue: string | undefined = undefined;
     return html`
       ${extraStyles}
       <div id="aspect-ratio" style=${styleMap(aspectRatio)}>
@@ -1008,10 +1009,11 @@ class ButtonCard extends LitElement {
         </ha-card>
         ${this._getLock(lockStyle)}
       </div>
-      ${this._config?.tooltip
+      ${this._config?.tooltip &&
+      (tooltipValue = this._getTemplateOrValue(this._stateObj, this._config.tooltip)) !== undefined
         ? html`
             <span class="tooltiptext" style=${styleMap(tooltipStyleFromConfig)}>
-              ${this._unsafeHTMLorNot(this._getTemplateOrValue(this._stateObj, this._config.tooltip))}
+              ${this._unsafeHTMLorNot(tooltipValue)}
             </span>
           `
         : ''}