Hi,
I'm Rodrigo and I'll help you.
To make the active tab more distinguishable from other tabs on Microsoft Edge, test the other theme colors on Settings > Appearance, some colors work better than others.
If It is not good enough for you, check the themes on Chrome Webstore:
https://chromewebstore.google.com/category/themes
Here is an example of a theme with the active tab in another color:
https://chromewebstore.google.com/detail/high-c...
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