Can only have one sitemap?

I’m using Rank Math and I am receiving this statement in my WordPress dashboard:

Please keep only one Sitemap plugin active, otherwise, you might lose your rankings and traffic. Click here to Deactivate.

However, I’m not aware I have any other plugin that would generate a sitemap. I USE to, but I deactivated and deleted it and removed the folder from the plugins folder in the file manager.

These are the plugins I have installed and activated:

• Back In Stock Notifier for WooCommerce | WooCommerce Waitlist Pro
• Fast Velocity Minify
• Flexible Shipping
• GreenPay™ by Green Payment Processing
• Jetpack by WordPress.com
• myCred
• Newsletter, SMTP, Email marketing and Subscribe forms by Sendinblue
• Porto Theme – Functionality
• PW WooCommerce Gift Cards
• Rank Math SEO
• Strong Testimonials
• Woocommerce
• WooCommerce Mix and Match Products
• WooCommerce Sendinblue Newsletter Subscription
• WooCommerce Services
• WOOF – WooCommerce Products Filter
• WPBakery Page Builder
• WPForms Lite

The thing is is that I had these plugins installed already and installed Rank Math yesterday and everything was fine and then I installed WooCommerce Sendinblue Newsletter Subscription and it gave me this issue and then I deactivated that plugin, removed it, deleted the folder via Filezilla and the error still remains.