Try this font settings out.

Depends on system font's capabilities, so may not work.

src/app.css

@@ -34,6 +34,8 @@ a.mention span {
   text-decoration-color: inherit;
   text-decoration-thickness: 2px;
   text-underline-offset: 2px;
+  font-variant-numeric: slashed-zero;
+  font-feature-settings: 'ss01';
 }
 /* a.mention:has(span).hashtag {
   color: var(--link-light-color);

src/components/name-text.css

@@ -8,6 +8,11 @@
     font-weight: 500;
     unicode-bidi: isolate;
   }
+
+  i {
+    font-variant-numeric: slashed-zero;
+    font-feature-settings: 'ss01';
+  }
 }
 .name-text.show-acct {
   display: inline-block;