Luna VPN is kinda a recuring theme in this sub. Their most promintent (blessing and curse) feature was their use of a MITM proxy to preform ssl intereception to block ads. On one hand this allowed them to block ads on hulu/youtube (normally this is dificult to do at a dns level since these sites use the same domains for serving videos as ads meaning nuking the domain breaks the app). On the contrary it means they can also see the contents of the websites you browse.
Here is an example of bank info that could be seen. I used a free open source program called mitm proxy to get this (similar to the approach of luna vpn).
By the same token they could steal login credentials/moniter other apps in a similar fassion.
Now lets say you don’t care about your literal web contents being monitored by a shadey company, another reason not to use them is well their app is pretty bad at blocking ads now. After being pulled from the app store and google play once the new version removes the mitm capabilites meaning it doens’t block hulu or youtube ads anymore (its only good feature).
As per alternatives on ios and android I would strongly consider using nextdns. They do not sell data like luna and don’t have a mitm proxy like luna vpn (trusted by chrome and firefox). Adguard is also another good pick though they give you a little less control on the filters/whitlists you can use.
On android you have a few more options from private dns to local blocking (a great video by howtomen):
https://www.youtube.com/watch?v=Iigq1kRnKxQ&t=532s
Finally regarding youtube and hulu. The best way to block youtube ads is by using a modded client.
For ios use uYouPlus sideloaded via altstore or sidestore. Main benefits is in addition to blocking ads uYouPlus allows background video playback, downloading videos offline, and blocking baked in ads via sponsor block.
https://github.com/qnblackcat/uYouPlus
On Android use revanced:
https://github.com/revanced/revanced-manager
As per hulu I made a old thread tutorial on how to block it on android (sorry ios users your out luck here) using firefox or kiwi (fork of chrome):
https://www.reddit.com/r/Adblock/comments/kbjx99/revisiting_hulu_adblock_android/
Older post:
https://www.reddit.com/r/Adblock/comments/dl57x9/luna_vpn_adblocker_potentially_stealing_my_info/