Alternating view mode not working

I'm seeing the same thing.
I checked with 3.15 on several D10 versions and the problem starts on 10.1.x.
The 10.0.x version does not have this problem.

It seems like the dsPreRender function is not firing properly since that contains the code to set the classes.
Code can be seen here: https://git.drupalcode.org/project/ds/-/blob/8.x-3.15/src/Plugin/views/E...

I used git bisect to identify wich Drupal core commit between 10.0.11 and 10.1.0 is the culprit.
Seems like it is this one: https://git.drupalcode.org/project/drupal/-/commit/eb019c17cfba31f5e76eb...
The commit is linked to this drupal core issue: https://www.drupal.org/node/2457999 →

I posted a notice there as well since I don't really know the scope of that ticket yet.

Yes, that core issue is being annoying. Tracking in 🐛 TranslationLanguageRenderer not using row style configurations Active