On your Tab demo page for Bootstrap 4 (https://blazor.syncfusion.com/demos/tabs/default-functionalities?theme=bootstrap4) the selected tab is not underlined and the unselected tabs are underlined to create a proper visual appearance. When I look at the Bootstrap 5 demo page (https://blazor.syncfusion.com/demos/tabs/default-functionalities?theme=bootstrap5) all of the tabs are always not underlined. I found the same issue in my own program. Is there a way to get the tab underlining to work like the Bootstrap 4 version? Thank you.
Works now on Chrome, thanks. However in Safari I still see an issue. When the leftmost tab is selected it looks proper. However when I select a tab further to the right, the newly selected tab is underlined.
Using your demo site on an iPhone 7 and Safari browser. When the first tab is active (Twitter) it works properly: the selected tab is not underlined. When another tab is selected (Facebook) all tabs are underlined.
The issue is reproduced on an iPhone 7, iPad 6th Gen, and iPad Air 4th Gen. All running iOS 14.8.1. My understanding is that Safari automatically updates to the version of the OS (i,e.,, Safari v 14 is on the devices). I don't have a browserstack account so will have to rely on your test results with that tool.
Good news. Updating iOS to 15.0 appears to solve the problem. So Tabs should work correctly on fully updated devices.