Passcode error msg from Zoom

We often have parents login in zoom for school online class session and Zoom return passcode error message. At our end, nothing is change, the only trick is
1) Get parents to clear the history and re-key in ID and passcode - most of the time this will work
2) Uninstall and re-install zoom - if step 1 does not work.

Is this the security feature from Zoom? But we do noticed only random parents have this issue, not every parent faced this. Anyone has experience and a good solution for this?