Most of the current Stream mods have been participating in this stream for a long time, have been mod before. It's easy to check that history. They have accounts from ~2020 or earlier.
There are a few current newer mods from 2021-2022. They have less Moderation history to review, so other things are looked at.
Some mods have been removed over the past few months for breaking the Terms of Use or Stream Rules, some new mods have been added. It's not one for one but as some go out the door, some new ones come in the door.