Pedantically, they're wrong, but the two are closely related.

They both use the parent's hash together with the contents of the block/changes in the commit to compute hash of the current block/commit.

Git supports many parallel branches, while Blockchain uses decentralized consensus mechanisms to keep the entire network in agreement and resolve branches as soon as possible. So yes, the mathematical problems in the two are different, but the data structure is very similar.

Source: my last job was creating developer toolsuits for Blockchain.

Y'all love to pretend blockchain is important and useful for all kinds of things. Just stop. It's shady to try to take credit for anything good in the hope that some of the goodwill rubs off on blockchain.

Git predates Bitcoin. It is also useful and efficient, things blockchain is not.

You cannot claim everything that uses hashes is a fucking blockchain, it's ridiculous.