It can be a perfectly normal, acceptable means of flocking a saddle. I’ve seen hundreds of quality wool-flocked saddles with such slits. My own saddles have them–one came with the slits (from the manufacturer) and my fitter made slits in the other.
It can also be evidence of a butcher job by a substandard saddle fitter–or in extreme cases, evidence of an owner or amateur fitter trying to DIY (that’s bad, obviously).
The size and location of the slits, however, is a matter of opinion and skill. A good saddle fitter will make them as small as possible and put them somewhere unobtrusive. But depending on the saddle, a one-inch slit in a more obvious location might be the only choice for on-site flocking. So without picture evidence, it’s hard to say whether you’re dealing with a hack job or “what any decent saddle fitter would do if tasked with adjusting this saddle’s flocking on site.”
If you like, take a picture and post it here. There’s plenty of saddle fitters on this board who can tell you if it’s legit or not.