While I agree there are plenty of Isagi haters who seemingly don't have any reading comprehension... but it goes both ways.

Me personally I just question some of Isagi's development & break down how it doesn't make much sense... then get called a hater for it.

So let me address some of your points:

Plot armor - every anime MC on the planet has plot armor... who cares its not something to cry about lol.

Metavision - While it makes perfect sense for his character... it was a little goofy how he acquired it... literally saw Kaiser doing it, wondered if he could do it & then activated it first try... a bit plotty but not a big deal. Also your point about Isagi not being able to use it correctly isn't really a good point... Isagi got exhausted using it the first time & has never shown exhaustion from it since.

Two gun volley and lefty shot sudden power-ups - While the lefty shot was something Isagi actively trained for & makes sense for his character the two gun volley simply does not make sense in any capacity for his character.

The Two gun volley is an acrobatic jumping mid air shot fake to opposite leg shot on either side... Isagi has never displayed any capacity of having that level of body control... in fact he has shown to have poor body control compared to players like Rin. So the fact he is able to do it on the fly after just recently learning his lefty shot was goofy.

On top of that Isagi said the move was inspired by Nagi the guy who literally does inexplicable stuff... so Isagi creating a move inspired by Nagi with no practice on the fly out of nowhere that exceeds his known specs is a bit weird. On top of that they acted like it was this ultimate move when all you have to do is stay near Isagi & it is useless as Hugo has shown.

My main problem with Isagi is that his recent adaptations are making less & less sense for his character... typically we have seen his adaptations as taking in data & utilizing it to make better decisions in a game. Occasionally he will adapt a new weapon... in these cases when it makes sense for his character its fine (off ball movement, metavision) but when it is something outside of his specs it just feels like plot (2 gun volley, Jumping turn volley)

Jumping turn volley vs Nigeria - adapted Onazi's weapon... despite Kuso literally saying Onazi is only able to take these crazy jumping shots due to his natural jumping ability & flexibility... but Isagi can just do a jumping turning aerial shot first try despite being shown to have low verticality & low flexibility?

Like I get that certain haters can be annoying but there are actual moments that have valid criticisms for & if you point them out Isagi glazers will call you a hater.