Omni has a feature which allows URL text in data to be displayed as interactive URLs in tables. This can be enabled in the table options for the field:
If you are attempting to use this feature and find that when clicking, it is appending your URL at the end of an Omni URL instead of opening the URL, double check if the URL in the dataset is a fully formed absolute URL with the protocol (i.e. has http://www. or https://) at the start.
If not, you can prepend this with a calculation or by editing the field to concatenate it into the string.
For example, if the value in the data is just omni.co the URL will not work; you would want to do something like CONCAT('https://',url_value) to produce https://omni.co and this should then work!