Bunch of probabilities.

1. If you have a new account, maybe you don't meet the karma and/or account age requirements for the subs you post in.

2. You've been shadowbanned. This is when you post comments and they never show up.

3. like someone else said, they might be linking your new account to your old ones based on your ip address or maybe some other metric.

4. like someone else said, there is not much reason to be on reddit anyway.

You know what, go to r/shadowban and post there. (any random self text post) A nice bot will come over to let you know if you've been shadownbanned and which of your 100 most recent submissions have been removed.

alternatively, visit your account page while logged out or on a diff account. If you're shadowbanned you will not be able to see the account page.