fix: remove problematic Markdown optimization (via #5520)

src/core/components/providers/markdown.jsx

@@ -15,22 +15,11 @@ DomPurify.addHook("beforeSanitizeElements", function (current, ) {
   return current
 })
 
-// eslint-disable-next-line no-useless-escape
-const isPlainText = (str) => /^[A-Z\s0-9!?\.]+$/gi.test(str)
-
 function Markdown({ source, className = "" }) {
     if (typeof source !== "string") {
       return null
     }
 
-    if(isPlainText(source)) {
-      // If the source text is not Markdown,
-      // let's save some time and just render it.
-      return <div className="markdown">
-        {source}
-      </div>
-    }
-
     const md = new Remarkable({
         html: true,
         typographer: true,