Zend certified PHP/Magento developer

Magento 2.4.3-p1: Prices in frontend excluding tax but should be including tax

After upgrading the shop from version 2.3.2 to 2.4.3-p1 all the product prices in frontend are shown without tax. The price in backend is correct, all settings in Stores > Configuration > Sales > Tax are set to Including Tax and yet the prices are shown without tax on all pages (catalog, product details page, cart, checkout). The Enable Cross Border Trade setting is set to Yes but setting it to No doesn’t help. We have 2 stores and I’ve checked all scopes but the settings in every scope seem to be correct.

What I tried and did not help

  • downgrade to 2.4.2
  • switch the Stores > Configuration > Sales > Tax settings to Excluding Tax and then switch it back again but that did not help
  • reeindexing, removing cache, reimporting the products
  • disable our custom modules

Magento version: 2.4.3-p1
PHP7.4
Mysql 8.0
Elasticsearch 7.9.3
Varnish 6.5.2