For example

"INSERT INTO luckperms_groups_permissions(group, permissions) VALUES (admin, {"permission.node": true, "another.permission.node": false})". Would look much better compared to current thingy

That breaks database design and usage and is a whole lot more inefficient for working with

Out of interest, why do you want this to be changed, and what would be the benefit of using this over the current system?

I myself can also not see any benefit from this.
If you want to store it as JSON, just use JSON storage I guess?
There is no real benefit for having the information stored as JSON on a remote database.

That breaks database design and usage and is a whole lot more inefficient for working with

Basically ^