Now there are massive blocking of Twitter accounts.
Most often, block accounts when you to use mass-following. Blocks is forever!
Also do not use hashtags #ICO #Cryptocurrency etc
Be careful!
UPD
Some accounts of my friends that have been blocked marked "forever" are now unlocked
But anyway, I think we need to be careful
Yes, We need to be careful. I experienced that when I shared many tweets from the ICO page on twitter, And I need to verify my account using my mobile number and once I verified they unlock again. But also take care to your twitter account without binding on the mobile because they can lock forever.
Even though we verify with our mobile number we have to be very careful with the tweets we are doing because once we are not following any rules and regulation of the twitter definitely they will ban us without any intimations.