Invalid Users being added likely from a bot attack on our site

Although we are using reCAPTCHA users are being added and likely from a bot attack on our site. In the past 30 days we have received approximately 1000 invalid registered users on our website. These are being added from what looks to be a Russian URL address. Here is an example of the User Name: 115 052 RUB TINKOFF telegram – @sibbnk. This one has an email address of [email protected] associated with that user. How do I restrict these?

The page I need help with: [log in to see the link]