There are many places where you can find work. upwork, fiverr, Gamasutra, GameDev etc as a freelancer.
Make a post on one of thous sites and tell a bit about yourself, experience & knowledge, (programing language etc).
And there is also Reddit. r/gamedev, r/adultgames
And Discord groups like AGD, Adult Game Developers. etc.
And lets not forget this forum.
However. one issue if that, gamedevs/studios are rarely just looking for some random dude to help out a bit with their work.
And Helping out with debugging is not as simple as it sounds like.
For that you should also Have experience with the GameEngine used, not only know some programming.
If you want to get into some of the serious games, imo better look/apply for a part time or a full time job.
Other than that, my best bet is to just lurk around formus like this and check the Dev section once in a while to see if you can help out developer or modders.