This post here https://steamcommunity.com/app/1262600/discussions/0/2967272951911335147/#c2967272951913902185 mentions disabling Overwatch lets background textures load normally. I tried disabling it and the background quality did get better, along with some ground textures a bit away from my car. However putting it back on didn't make the textures worse again, even with restarting. Is anyone else able to confirm this? I'd add it for "issues fixed" but it's hard to prove if it's just that setting that does it or if it's changing lobby settings as well.
For the record, mine is set to Friends lobby with Overwatch off and the background textures are loading fine now for me.