Subreddits are influenced by the Reddit algorithm where popular, leftist things end up on the front page and you may be influenced by them even if you never asked to see that stuff. Only way to not see is make a conscious effort to stay on Home. Even that doesn’t make you immune because Reddit will suggest subreddits that you may not necessarily want to see content.

Discord is different because you have to intentionally join a leftist or conservative chat channel and the content is not suggestive.