Zero conditional in indirect speech
When we report zero conditionals, the following tense changes may occur:
Present time
Anne: If John is cursing, it means that he is very angry.
Anne said that if John is cursing, it means that he is very angry. (it is still true)
Anne said that if John was cursing, it meant that he was very angry. (referring to a past habit)
Past time
Jenny: If I got home late, my mom scolded me.
Jenny recalled that if she got home late, her mother used to scold / would scold her.
Note that past tenses in the if-clause do not normally change.