Hi @kyakouty – thanks for the additional detail. I can confirm that nothing in balenaOS or Etcher locks the SD card, makes it read-only, or prevents it from being formatted.
Depending on the size of your SD card, I wonder if the write-protection switch (that is, a physical switch on the SD card) has been set. Can you have a look at https://kb.sandisk.com/app/answers/detail/a_id/1102/~/sd%2Fsdhc%2Fsdxc-memory-card-is-write-protected-or-locked and double-check this?
All the best,
Hugh