Earlier quoted context omitted.
Not in the slightest. No different than a player playing optimally or with tight adherence to a strategy like Brunson's SuperSystem. Game Theory Optimal Poker is just the given when playing MTT - although many platforms have some form of Real Time Assistance detection. Even in live games they use poker solvers in between breaks to optimise your playing potential and reduce the range of 'playable hands'.
Yes in the fullest. For one thing it's against the ToS of every site. But it's also just plainly unethical. Even the most elite players are merely reaching a moderately accurate approximation of optimal play, which completely pales in comparison to a bot that can find it on every hand. Of course a bot that simply assumes opponents are playing co-optimal strategies will only be minimally exploitative, but more sophist…
As for unethical, things like PioSolver, MonkerSolver, and PokerSnowie are basically de facto standard for play at high level online - and are absolutely used at breaktimes in live play. Then you have people multi-monitoring, or running GTOWizard in a VM, as a given.
You're basically claiming that all bots in action are Pluribus style, which is just nonsense. I bring up SuperSystem since its the earliest reference I can think of by a Pro to the concept of range advantage.
The modern poker sites basically just teach game theory optimal... which ends up with people running GTOWizard as a given. The best bots I've seen that avoid detection are basically doing some variant of the strategies outlined in modern guides like RIOs From the Ground Up.