Code works with Deprecated - Arduino Mbed OS Boards but doesn't work with Arduino Mbed OS Nano Boards

I am pretty new to Arduino.
I am using: Arduino nano 33 BLE board, Arduino IDE 1.8.15.
I am facing a problem that my old code doesn't work with the package: Arduino Mbed OS Nano boards, but my code works with the: DEPRECATED- Arduino Mbed OS boards.

My questions are:

  1. Will there be one day that I can't download the DEPRECATED- Arduino Mbed OS boards from the board manager? Any suggestions for this case?

  2. If I would like to use the Arduino Mbed OS Nano boards, I will have problems with the "interrupt" portion of my code. Any suggestions on how can I update my code so I can use this package instead of the DEPRECATED one?

Thank you

Which version?

If you open Tools > Board > Boards Manager, you will see the version number of the "[DEPRECATED - Please install standalone packages] Arduino Mbed OS Boards" platform that is installed.

Please provide a detailed description of the problem.

Include a complete minimal example sketch we can use to reproduce the problem.

If you are getting any associated error or warning messages, post the full and exact text of them here.