It is completed intended to not be able to receive hextech loot even after your chat restriction is up. You need to show consistent, improved behavior across many games in order to start earning loot again. The amount of games will be different for each player as it is dependent on your own behavior. From what I've seen reported from other people, this can take anywhere from around 30 games to 100+ games, it just all depends on how quickly you show improvement. If you continue to show negative behavior, then it will take longer to become eligible.
For more information, you can read this guide:
https://support.riotgames.com/hc/en-us/articles/209939463-Hextech-Crafting-Restrictions