Twigtweak breaks preview, also TypeError: Drupal\twig_tweak\TwigTweakExtension::drupalField(): Argument #3 ($id) must be of type string, null given

Note the third parameter of drupal_field(). It must be ID of the node. When previewing a new node the ID is NULL because the node is not saved to database yet. If you have access to node object in your template, it's always better to use view filter instead.

Example:

{{ node.body|view}}
{{ node.field_announcement|view }}

Just to confirm, there is a problem even when this node has already been saved. This breaks the ability to preview and instead of seeing a preview the editor sees the last saved copy. What's more there is no error message but the preview is broken. Because there was no error it took quite some time to track this problem down to twigtweak.

PS it seems like in this circumstance I can get away with using
{{ content.body }}
and
{{ content.field_announcement }}

Thanks so much for your help!!!

a preview the editor sees the last saved copy.

That is expected behavior. drupal_field always loads node from database, it does not care of what you are previewing.
This function is typically used when the node variable is not available. Otherwise {{ node.field_NAME|view }} is preferable way to render a node.

Awesome, I appreciate your fast reply and for upping my twig game!