It's hard to tell which tab is active in the light color scheme

[Pablo-fdez]

Basically the title. In dark mode the active tab is a bit lighter than the rest. In light mode they are all a very similar color:

[ghost]

Faced a similar problem. But, after a while of usage, I could determine the difference.

[Pablo-fdez]

Yes, actually now I think it might have something to do with my brightness settings.

[strindhaug]

Yes the contrast is way too low to be accessible. Also the fact that the tab bar changes color depending on the website (manifest file, I assume?) makes it even harder to see the minute difference in color of the faintly highlighted tab because "everything" changes.
Ideally you should be able to set the highlight color yourself, and disable the changing of tab-bar color.

[strindhaug]

Just realised, I can disable site themes and choose always night theme. Though I'd still prefer to set the tab bar color and highlight color to something I can see, without also enabling dark mode on all websites that support it.