Is it against TOS to use this tool?

[MPK]

That seems more OP than automatically placing markers

[Packetdancer]

As far as I'm aware damage parsers are the only third party tool where SE acknowledged their use and stated they won't actively hunt down people who use them.

They've also acknowledged ReShade/GShade/etc. as being used before. And they've said that while they prefer to be able to pretend not to see it, they also don't particularly care to enforce that one; it's still technically against TOS—as is any external tool—but gives no real advantage as opposed to just making the game pretty. The one thing they've openly asked is that if you're using ReShade-like post processing or shader injection to please not stick the Square-Enix copyright notice watermark on the bottom like normal in-game screenshots have, as they'd prefer shader-injected/post-processed stuff not be mistaken for the stock game.

I mean, that one's a weird case to start with, though; Nvidia now has a version of ReShade (literally ReShade, not just "something like ReShade") embedded in their GeForce drivers now anyway as "Freestyle", and last I checked Square-Enix let FFXIV be added to the supported games list for Freestyle on the Nvidia website. So it's clear their objections there are minor at most; even if the ReShade family of tools were actively cracked down on for some reason, anyone using a ReShade derivative could just copy their ReShade stuff over into Nvidia's version which SE has evidently officially sanctioned.

[Seddrinth]

ok I guess it's 'ok' to use as gm won't do anything to players using that zoom tool

if you don't let anyone know then you probably are ok

[moshev]

Well, it would be trivial for Square to detect you're using it - just check the FOV and max zoom values in memory now and then, and if they're different from the defaults, ban. No need to scan for the tool running, as it literally changes values in memory, which is technically a form of hacking.
That said, I think Square should just give us a FOV slider and allow slightly farther zoom. Even competitive FPS games like Overwatch and Halo let people select what is comfortable for them. I don't see people with 100 FOV having an advantage over people with 70 FOV in PVP, it's all a matter of what is comfortable for you. You can also always track enemies on the minimap. I also haven't heard of anyone advocating zoom hack's use to gain an edge.
I don't play PVP, for me it's all about comfort. The default FOV is too small and I can't see as much of the world as I'm used to. It makes it easier to also see all the cool boss animations when you're right up their butt, too.