It more in the context of the theme. If the block is only for design, formatting so should it leave inside the Theme. However is also possible as plugin, because so it is possible to use after a switch of the theme or separately. But is the block a part of data, they're stored inside the database and have more a topic of data, not only design so should it a separate plugin, not inside the theme. It makes also much more easy to update them.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
It more in the context of the theme. If the block is only for design, formatting so should it leave inside the Theme. However is also possible as plugin, because so it is possible to use after a switch of the theme or separately. But is the block a part of data, they're stored inside the database and have more a topic of data, not only design so should it a separate plugin, not inside the theme. It makes also much more easy to update them.