I may be missing something, but I dont think any of the complaints here hold any water.
Button bloat: you shouldn’t really be using both mind spike and mind flay, there’s builds that use one or the other, but in pvp im sure you should be going mind flay for its slow component. The flow is smooth as well, due to mental decay you dont have to think about dots as much, lots of instant cast procs to keep you moving and agile. strong burst windows where you cycle between DPlague, mind blast, and void bolts. I think y’all are just doing something wrong.
Lack of peels: Shadow has plenty of survivability, but its never been a strong peel class for itself. thats why it was always paired with classes that could focus on peels more like PMR, rogue/priest, druid/priest, etc. that said i feel like between void tendrils, fear, dispersion, desperate prayer, a shield on hitting low HP, silence, and psychic horror you have plenty of options to keep yourself safe in a pinch.
Nerfs/weak class: You say that there were nerfs but priest only saw buffs in 10.0.5. I actually stopped playing my other few alts because priest feels so solid right now in all its specs. You have tons of utility, tons of damage, and tons of healing. You say healing became toxic, but there’s so much burst in the game for the last few expansions im not sure what you want people to do to satiate your ego. In Shadowlands warriors could almost one shot people, on my rogue i could shadowy duel people with BoP to send them to their own realm where they wouldnt even know they were being attacked until the screen flashed red, etc. Outside of organized competitive content you’re not going to be the primary focus of players, same way you arent thinking of others when you’re in a fight.
Major CD that buffs dots: you mean something like screams of the void which already amps dot dmg by 80%? Mind trauma which amps your haste by 12% while sapping enemies? void form granting 20% crit on use (though it fades)?
I honestly think that your posts come from a place of wanting to do everything yourselves despite complaining that all the classes feel the same. Its ok to not excel in 1v1s or be able to hold your own in every match up. priest excels when its given a bit of breathing space and then explodes someone with intense pressure, thats how its always been.