Shadowbans are not account wide.
You can have content deboost bc all kind of things. Nsfw, hashtag use, spammy account boost. It is post related and can be removed by finding and deleting post. Also if you get reported and it sticks. I dont see links causing anything. More if you have it on all posts.
Reply deboosting. Spam comments a lot, threatten people, talk shit too much and you posts will go into "see more replies" , but not "these comments may be spam".
Search ban. Quite common. From what I see happens on profile edits, acc changes, birthday changes. Even when you delete too many posts at once. Goes away, or doesnt. I dont see it matter much and I can find most if not all profiles I search for.
You will not be shown in recommended follows of pages and on yours it wont show similar pages.
One more, is profile getting temp suspension and a warning showing when you browse it. I never had this one.
Phone verifications and captcha shows up when you do stuff to fast. Automated or not.
Twitter algo is good and it keeps communities very separated. You have to "train it" to show it to you.
Buying profiles is normal, lots of botted ones but they can get banned on blue verification. They do manual reviews for checkmarks. Got few accounts suspended.
What I would do is change pw, delay, change profile details, delay, post a bit, after some time, on same clean IP, go ask for verification.
Each name profile or @ change it will review manually. If shit has been done it it prior to changes, they will see it.
Temp VC dont work for twitter anymore sadly, but you can use non-onetime virtual CC.
Dc proxies are okay, they do the job. I always pick usa and change profile country and lang to match.
Real SIMs, 1 for 2 profiles. Keep track of it you will be asked for it if you run over limits.
1st login
if clean real IP it wont ask anything
Enter phone number on clean DC
Get code from phone ALWAYS if attached and code from email for not-so-clean ip.
Bad ip usually has troubles with codes
I have profiles running for a years testing stuff, getting all kinds of errors, limits with low % of them getting totally fucked.
Started with shadowbans ended up a bit longer. Things are not what they used to be on Twitter. Hope this helps anyone.
P.S. I have always used aged accounts, will stop when there are none. Now you have to warm them up and everything and they will never have same "trust score" as ones few months or years old.