Warning: Undefined array key "commerce_product_attribute_value" in views_order_by_delta_views_data() (line 25 of modules/contrib/views_order_by_delta/views_order_by_delta.views.inc).

This patch will resolve the issue.

@saurabhkanva please provide the fix as MR!

I don't understand, how this fixes the issue?

$data[$entity_type->getBaseTable()][$table_name . '__views_order_by_delta'] = [...]

already creates $data[$entity_type->getBaseTable()] automatically.

I have to agree with @grevil.
This is btw line 25 (since 3 years):
foreach ($entity_field_manager->getFieldStorageDefinitions($entity_type_id) as $field) {
https://git.drupalcode.org/issue/views_order_by_delta-3382073/-/blob/338...

Wondering how the Undefined array key can appear there?

@anybody, my exact thought as well, but I just found the reason.

3.x is still in alpha for some reason, so he was still using 8.x-2.x, where this exact behavior can happen, see https://git.drupalcode.org/project/views_order_by_delta/-/blob/8.x-2.x/v....

@saurabhkanva please use 3.0.0-alpha1, which should fix the issue.