Long catalog names doesn't show up fully, shows up partially followed by three dots(...) when opened through service catalog on Service Portal
It is an expected behavior in London Service Portal.
There are changes in the widget code from the prior version to London which is causing the behavioral change.
Under the widgets (SC Category Page, SC Popular items) Body HTML template field, catalog names are coming from the h2 tag. Within the h2 tag, there is a class named text-overflow-ellipsis. This is responsible to show the title partially.
The catalog item name is 'Add network switch to datacenter cabinet'. But it appears as 'Add network switch to datac...' as follows
This can be seen in London while using 'SC Category Page' or 'SC Popular items' widget