As another user, I was intrigued since there are literally hundreds/thousands of support posts. So I looked back to see what your question was.
You asked one question about something that has nothing to do with the plugin but is basically user error. You said you installed it, tested it by creating galleries, removed the plugin, and still had NGG references. Of course you did.
You created galleries to test it, they don’t magically disappear if you remove the plugin. Just like EVERY other plugin.
If I run a block plugin, add blocks, and delete the plugin, the block codes are still there. They won’t work anymore, but the codes are still there. You removed the plugin, not the code.
You can put gas in your car with a hose, remove the hose, the gas doesn’t immediately disappear. If you want to get rid of the codes you put in, you have to go through and remove them. That’s why people create staging sites to test things.
Your claim there are better alternatives is laughable…if you have some, let’s see them. Meanwhile, NGG is the #1 gallery by a considerably wide margin, in the top 10 of all plugins across ALL of WordPress.
Paul