(confirmed on v4.3.2)
Steps:

• Go to Shipping management and add shipping costs to DE
• Configurate VAT for DE similar to:

  ibexa:
      system:
          site:
              product_catalog:
                  currencies:
                      - EUR
                  regions:
                      - DE
      repositories:
          site:
              product_catalog:
                  engine: default
                  regions:
                      DE:
                          vat_categories:
                              standard: 19
                              reduced: 7
                              none: ~
  

• Set VAT for product type 'foo' to 'standard'
• Add product having product type 'foo' to basket
• Go to Checkout
• Fill delivery address to Germany.
• Go to Summary.

Result:

• Shown VAT value does not include the VAT for the shipping value
• Reloading the page updates the VAT to a correct value