Users have noted that the Dark Mode is not working in Google and Google Assistant apps on Samsung phones running on the Android 10. This problem surfaces when the Dark Mode theme is activated.

This new bug appears to have snuck up with the recent updates, with a number of other Android users like OnePlus also facing this same problem. However, the app is still working properly on Pixel phones. The Dark Mode feature seems to be faulty on the Samsung Galaxy A70s, which also has the latest version of the app. However, some users are yet to experience such difficulties, with others saying that the bug has been fixed on their phones. This problem may be due to a server-side switch or may be a problem with the app itself. Whatever the cause, we hope that Google will identify and fix this bug as soon as possible.   References

Samsung Galaxy Users Are Losing Dark Mode In Google Apps   MobilityArena - 28