Interesting question.
I'm not sure if there are any commercial restoration services. I doubt many bike shops would want to take that kind of work on unless the owner had a personal interest.
I wonder if there would be the chance of a local forum member doing it, but there's a whole big can of...
When the bikes are of such high quality it comes down to the finest of margins in choosing who to vote for, and photo quality is one of them. It was the only thing that separated the winner this time for me.
These are awesome and this looks like a nice one.
Please buy it so the temptation goes away!
https://www.retrobike.co.uk/threads/1997-saracen-kili-team-price-drop.445660/
You asked if it was a factory weld or a repair.
My answer is it's neither. It's a bodge. It may have lasted, but it is still shoddy work of the lowest order.
You've asked for an opinion. I've given mine for free. You may not like it, and if so, I give a full money back guarantee. HTH.