Yoapi
I have a question.
Does getting banned a few times
change the chances of being able
to become a moderator ?
It's a case by case situation, but in general having several accounts that were banned wouldn't look very good on an application.
While the team is quite tolerant regarding warnings (because they believe in people evolving, learning from mistakes and getting to know the rules better over time), banned accounts mean you've been violating the rules in a way that was serious enough for the Admins/Moderators to decide you shouldn't be able to keep using that account. If you've repeatedly been banned, then it's looking even worse as it wouldn't show you've been evolving, learning from past mistakes and/or making efforts to follow the rules).
If you had a warning for spamming 8 years ago then nothing major since, it wouldn't be held against you as chances are great you grew up after all these years. However, repeated bans would show you have a serious issue with complying with the rules. Ask yourself this: How would that make you a good potential moderator in the eyes of the team that reviews application? As a moderator, you'd be supposed to be an example, and know (and follow) the rules perfectly.
Of course, this doesn't apply to bans that were placed for security reasons or bans that were reversed later (if your account was compromised, for instance).
Like I said above it may vary depending on your own case (and you would only get a final answer after your application has passed the review process), so if you still believe you have qualities that would make you a good candidate, you're welcome to file an application.