If you’re re-adding the ability to view past usernames then please try to look into a possible way of letting us hide our past usernames. If moderation is that big of an issue, you could always just make it so that a past username must have been changed x months ago before it can be hidden, or that the user must be phone-verified, etc.
I was so excited when I first saw this, until I realized that this is only temporary, and that past usernames are coming back in December. I have so many reasons why I want to hide my past usernames.
The “Hide Past Usernames On Profile” feature request thread was created over 5 years ago and has over 500 likes, with plenty of people giving their support and reasons behind wanting it.