Good point!

As bitcoin is permissionless, it is an interesting topic.

I see 3 solutions with different protection levels:

1️⃣ You remove your lightning address. You won't get any zaps, but also no spam.

2️⃣ You set a minimum invoice amount to your address with a lightning proxy. You can get zaps, but not small. You can get spam but not small.

3️⃣ We can make a way to define your minimum zap amount without setting minimum invoice amount. You can get small zap, but only big spam. Unfortunately if someone wants, he can bypass this if not enforced.

But if people can't spam with my app, they will do other ways as lightning allows it. So option 3 is not really "trustable". So lightning proxies have to be smarter I guess to set minimum invoice amount per user basis. So you can allow specific users lower minimum invoice amount. But this can also have disadvantages.

The sooner spam evolves, the sooner proxies will emerge I guess.