Being indexed is not an unchangeable status. Every update, especially change in payments, can temporarily delist a project. And games can also be delisted temporarily without updates. Some even get quarantined.
If you activated payment for the first time, that is a likely explanation.
Read that part of the sticky faq again:
"Why did my game disappear from the site? It was visible before."
When you make certain changes to a game page, it gets flagged automatically so that someone from the staff takes a look again. Exactly what changes count is a secret so people don't try to cheat the system. You probably did nothing wrong. Please wait.
And to be clear: none of your games are indexed at the moment and none of them are quarantined. Searching by username does work! Also, if you are underage, read that part of the tos, please. https://itch.io/docs/legal/terms#2-users-and-publishers