Chrome, Edge, Opera
In the Network panel, right click on the network request, and select "Block request domain". This will open the Network request blocking drawer that will let you manage blocked network requests.
Firefox
In the Network panel, click the "Request Blocking" icon to open the Blocking pane in the left sidebar.
Add the domain name in the input box to block all the matching requests for that domain.
Safari
In the Network panel, right click on the request and select "Create Response Local Override" to open the Sources panel, which contains the list of all local overrides.
Right click on the override and select "Edit Local Override...". Add the domain name in the URL pattern and use Status as
404: Not Found
to block all the network requests for that domain.