My rule of thumb is to deliver something you have “control” over and clearly shows the work was completed/delivered as advertised.
For example, when offering web design services, I would recommend against delivering with just a link to the client’s new website on their own server. This is because you have no control over that. Worst case scenario, if there was a dispute (maybe the user broke something, deleted the site etc) how do you prove what was at their URL?
When I offer web design services, I build the site on my own development server. At delivery, I then provide a link to the site I’ve built along with a backup of the files I made. I then offer to move the site onto their servers for them (for free). This covers myself by always having a development copy of the site to refer back to in any resolution case.
If I perform web design work (such as bug fixing) directly on a client’s site, I take live screenshots (using a software called ShareX) as well as Gif videos of any functionality I need to demonstrate (such as a hover-over effect etc).
Hope this helps!