"A battle arena is an arena by any other way you call it [...]"

Only as long as it does not cause confusions due to the titular level layout only found in Arcade gates and the other one sharing a similar yet lesser pattern found only in missions, but that is true.

"[...] its extra loot that imbalances the floor to the regular payout, so yes, it is different than a floor with energy gates that only lead to boxes"

So long as we mention imbalance between this case and the rest, I would sooner call out much of the rest of the level types for being disproportionately low in content and/or high in length, in that order.

"Those are events, which themselves are exceptions to multiple permanent-content conventions"

I would argue that they should not be event-based in the first place, but your point is taken.

"[...] if you want the jelly green giant to be an event [...]"

I strongly suggest that we do not bring such crazy and asinine thoughts to the table when it is painfully apparent that this increasingly flawed manner of implementing level content is amongst the least of what the game needs at the present.

In other words, absolutely not.

"Sure, if you want to add fighting rooms to other depth types feel free to suggest it [...]"

I recall there having been several suggestions on this matter up until now, mostly towards the case of Wolver Dens.

"[...] but it doesnt change that this one is still disproportionate to them"

While I agree to some extent, this requires no repeat in my arguments.

"[...] think vana vs a regular mission, sure you can tack on floors and make them 5 depths for content, but vana will still outweigh them"

You severely underestimate the potential of level design. Outweighing the loot payout rating from Firestorm Citadel would really not be all that difficult to accomplish.

Also, to be fair, the mission King of Ashes is itself by far the most regularly visited and revisited mission there is. Merely throwing it out there.

"I wouldnt consider a few preset rows of gun puppies a danger room, its easily less difficult than the final arena on that floor due to the ability to pick them off safely and one at a time"

The ability is on the side of the player, the room itself only provides a chance to do so for knights with long-range options. The situation is significantly altered when swords in general are the only options in hand.

"Unless the floor itself is to change in removing the exploit (so its just one arena with a few extra boxes as a net gain) then the imbalance point still stands [...]"

Calling it an exploit is a mistake when it is very clear that Jelly Farm is designed with the clear intention that knights can have the option to clear both rooms and collect the extra boxes at the cost of energy.

"[...] ill note tortodrones which were originally in those depths but were taken out fully [...]"

Only because they could consistently drop a 4* shield upon defeat. The unaccessible danger room within Jelly Farm was closed down due to being "too challenging to new players", yet it was followed with different options for difficult fights that gradually rendered this reason obsolete over the years. By now, there really is no valid excuse.

"[...] (and we know grey havens can cut the room out entirely due to previous floorscape modifications) [...]"

Yes, which would be a regrettably poor decision should it turn out to be the only modification applied on this matter. Which leads to...

"[...] so theres that option of just making a new aurora isles level and cut/pasting it into that"

That is very interesting, I had not considered that. If this is to be the ideal solution, then it may be time to separate the Jelly Farm levels from the other two in terms of sharing the same depth rotation and adjust them to appear one after another in an Arcade gate. Of course, that would be assuming there is either a return of the Sea Petal Pass level or a brand new addition to go with the Low Gardens and Stone Grove levels.