H4 visa extension when H1B changed employer


I went to India last year and got my H4 visa stamped until May 2022. I returned to US in August 2020. My husband did not travel to India after his extension approval and thus does not have a H1B stamped visa (his visa in passport expired in 2019). He switched his job in August 2020 and his H1B transfer was approved recently until late 2023.

Question -

  1. Do I need to apply for my H4 extension again or my current stamped H4 is still valid ? ( His previous employer could have revoked his prior H1B but not sure if they would revoke my H4 extension as well which they filed)
  2. Am I allowed to file for H4 extension now so that it is approved until late 2023 or should it be filed only 6 months before current expiry (May 2022)

Appreciate your response. Thanks in Advance !!