Hey there, @momo-fr! Thanks for contacting us. I’m happy to help you.
Just to confirm, it shows you have 3 order notifications, but only two show on the order page, correct?
Can you please reset your router and access your website from a private window to check if the wrong notification number is a cache issue?
Do you have any orders on draft?
If you filter the orders to only show the orders processing, it still only shows 2 orders?
Furthermore, I’d like to understand your site properly. Please share with us the necessary information below for us to investigate the issue further:
System Status Report which you can find via WooCommerce > Status > Get system report > Copy for support.
Fatal error logs (if any) under WooCommerce > Status > Logs.
You could copy and paste your reply here or paste it via https://gist.github.com/ and send the link here.
Looking forward to your reply.
Have a wonderful day!