https://bugs.winehq.org/show_bug.cgi?id=46148
--- Comment #19 from Vitalii Stoianov vitalii.stoianov.ua@gmail.com --- While wow is not playable on winehq-staging=3.20 you still can play it on winehq-staging=3.19.0~bionic
For that purpose I installed "aptitude" pkg as It has better dependencies resolution than "apt-get" pkg and installed winehq-staging=3.19.0~bionic before doing install I removed all previous version of wine that was installed on my system. This solution works for me now game is playable again no issue with textures.
sudo aptitude install winehq-staging=3.19.0~bionic
Also you can froze this pkg from updates till they fix winehg-staging to work with wow in future versions.