This is an example of hacking.
https://www.reddit.com/r/hearthstone/comments/rioa94/this_is_what_animation_cheating_in_hearthstone/
I think hacking is kind of an abused term it can mean anything the speaker wants it to.
I would define hacking as
- Modifying or reading memory of the game client to gain an advantage that would be otherwise impossible to gain.
Or
- Gaining access to the server and establishing a means to gain unfair advantage, typically by theft or malicious code injection.
The vast majority of hacking is of type 1 because it just requires modification of the game client. Type 2 hacking is much more difficult and requires the hacker to circumvent any security Blizzard has in place to prevent this.
Although type 2 hacking is not unheard of in games it is far rarer as it usually carries far more legal ramifications if caught as well as generally being a lot harder.
Typically you see type 2 hacking only when money is involved, say like crypto exchanges back when crypto was a thing. There needs to be a big enough payoff to motivate the people with enough skill to get the job done.