Why can’t one switch back to the default mode on Magento 2?

To switch back to default mode, open:-

app/etc/env.php

And change:-

'MAGE_MODE' => 'developer',

Back to:-

'MAGE_MODE' => 'default',

And re-deploy static files again.

reference:https://magento.stackexchange.com/questions/112523/why-cant-one-switch-back-to-the-default-mode-on-magento-2