this seems to be an chicken/egg problem..
when updating drupal/obfuscate_email to its new version via composer drupal/rot13 will be removed because it is not the modules dependency anymore. however it remains active in the drupal database it is now shown missing.
workaround
1. downgrade to old version via
composer require 'drupal/obfuscate_email:^1'
2. uninstall rot13 (this will uninstall obfuscate_email as well as it is a depenency) & clear cache
drush pmu rot13 -y && drush cr
3. require new version
composer require 'drupal/obfuscate_email:^2.1'
4. re enable module & clear cache
drush en obuscate_email && drush cr