There is no easy answer to the question of whether a guy talks about whether his ex doesn't like you, because everyone's situation is different.
First of all, a guy talking about an ex doesn't necessarily mean he doesn't like you. Sometimes, guys simply want to share their past experiences, including their relationship with their ex. This does not mean that he has any prejudice or resentment towards your feelings.
However, if a guy often talks about your ex in front of you or even compares you to your ex, it can be an unhealthy sign. This could be a sign that he isn't emotionally committed enough to you or that he hasn't fully let go of his feelings for his ex.
In addition, if the guy often mentions intimate details or negative experiences with his ex in the course of his relationship with you, it may also be a sign of disrespect for you. This can make you feel uncomfortable or neglected, which can affect your relationship.
In conclusion, it is not easy to tell if a guy likes you when he talks about your ex. You need to observe his words and actions and understand his emotional state and attitude. If you feel uncomfortable or unsure, you can communicate openly with him and ask him how he feels and what he thinks. Most importantly, respect each other's feelings and boundaries and build a healthy, equal relationship.