Custom Font doesn't work for newsletter block

I currently have some CSS for a custom OTF font I uploaded, It works across all Headings except the newsletter form.

I have tried a few methods I've found on these forums, but nothing has worked, it just changes it to the paragraph font, this is what I've used so far:

@font-face {

    font-family: 'FontTitle';

       src: url('https://static1.squarespace.com/static/6655e8b66a3cb20d523b1bd1/t/666887df7db23d789c82b082/1718126559744/PPTelegraf-UltraBold.otf');

  }

h1 {font-family: 'FontTitle';}
  h2 {font-family: 'FontTitle';}
 h3 {font-family: 'FontTitle';}
h4 {font-family: 'FontTitle';}

h1.newsletter-form-header-title {
    font-family: "PPTelegraf-UltraBold" !important;
} 

Thank you so much, I apologise I didn't see your response before. 🙂