YouTube mp3 is closed but there are alternatives -
Everything You Need to Know About Converting YouTube Videos to MP3: From the Best Converters to Legal Considerations - Neon Music - Digital Music Discovery & Showcase Platform
YouTube to MP3 Converter--YTBsaver
Top 3 Apps to Convert YouTube to MP3 on iPhone for Free
YouTube MP3 Converter
Top 10 Best YouTube to MP3 Converters - ANIMOTICA Blog