If I'm not wrong, the CVV code almost always follows a certain pattern based on the credit card number and dates. What are the possibilities to go through to hypothetically brute-force a CVV code? Is an online attack possible?
Actually it was possible, at least for Visa cards. There was no per-card lockout across the entire network, so by hitting different payment processors (to prevent from reaching any brute force limit they might have) you could brute force a CVV2. I am not sure whether this is still possible, I would expect (and hope) that Visa implemented network-wide protections against this.
If I'm not wrong, the cvv code almost always follows a certain pattern
No you are wrong, it could be completely random, 3, 4 or n chars.
After some failed activity with the card(could be 3, 5 etc...), it will be disabled. Plus you need to provide captcha for every request.
Sounds like you are much into hack rather security. A hacker at first is a great security geek.
No. It is not possible Cryptographically brute force. CVV generation uses one round DES and one round Triple-DES encryption and then first 3 numeric digits are selected from output(decimalization). As strong cryptographic algorithms are used for generation it is not possible to brute force CVV Cryptographically. Refer to my answer : https://stackoverflow.com/a/59116013/6225803
Yes. CVV generation being lossy encryption which produces 000-999 values. If you can make 1000 attempts and issuer does not block card after defined failed attempts.