Have you tried to post with a variying amount of hashtags , but posting every day? And staying active + viewing ads in home feed? Then taking a week break?
Also, do you have foreign language on your profile? (Name, bio, etc)
I noticed within 3 weeks of using my account normally (last week being a break) , just avoiding 30 hashtags per post in comments - it was back after editing some wording & maintaining human actions. No taking out hashtags , etc.
I was extremely shadowbanned too,
My name was "example"
If you searched "exampl" you'd see everyone except me, unless you searched "example" specifically. And I'd even be ranked last below people who have completely different usernames , their "bio name" had more rank than my whole igSEO'd account (example: if you searched "dexample" my authority was soo good I'd still rank at the top)
After acting completely human I'm off Shadow ban & earned #1 rank again
Edit:Example:try 1 day , #love. Next day try #cutecouples #bestfriends, next day try #bff #tbt #lovinglove , 4th day try #goals, and repeat
Normally people don't use the same amount + same hashtags , so flip a switch