This bug already was fixed in the "UI for Blazor 5.0.0" ("ComboBox dropdown will not open or close in Safari")
https://www.telerik.com/support/whats-new/blazor-ui/release-history/ui-for-blazor-5-0-0
I have "Telerik UI for Blazor 13.3.0" on Safari 26.0 and 26.5
This is can be fixed by "Clicking outside the component can mitigate the problem"
@Aleksey - do you reproduce the problem on our online ComboBox demos? If yes, then provide the exact steps or a video. I have Safari 26.5 and the dropdown opens and closes just fine no matter where I click.
On a side note, please ask the license holder at your company to assign you a commercial license. If you are still evaluating the components, then activate a trial. Either option will ensure that your account is in good standing, compliant to our license agreement, and able to receive technical support from us.