If you can now successfully add the contact to a WhatsApp group , the block has definitely been removed.
Keep in mind:
When someone blocks you on WhatsApp, it's like they're putting up a digital "do not disturb" sign. They won't receive your messages, calls, or status updates, and you won't be able to see theirs. It's a way for them to establish a boundary and protect themselves from unwanted interactions. Blocking someone on WhatsApp can be a drastic measure, but it's often necessary in situations where: if someone unblocks you on whatsapp