We had a canter through some of these issues in this thread (before the thread drift kicked in) . . .
The issue here is that, as a buyer, you can use filters and the like to find things that you are looking for, but those lists are
not necessarily complete because it now requires the seller to not only select the best
category, but also to set the
filters correctly (and many sellers don't set any filters at all). "G Gauge" used to be a sub-category, under "Model Railways" which was under "Collectables" (here in the UK). Now the category under "Collectables" is "Model Railroads & Trains" then the next tier down is "Railroads & Trains" (unnecessary???) and the only categories under that are "Locomotives", "Wagons", "Track", "Coaches" etc. No segregation by gauge/scale, which is what most buyers would want.
Since the change occurred, I have saved as a Favoutite a seach with no search term but just the "G" filter set (though that still means that I'm not seeing the items listed by German sellers under "IIm"). I do this for "Continental Europe" (UK plus any items in the EU where the seller is willing to post to the UK, even if at exhorbitant rates). Just now, that search delivered 5399 matches (though by using "Newly listed" and "Ending soonest" I only need to view a much smaller number of them). If I add the search term "LGB" there are 8300+ matches (still in "Railroads & Trains", but there is no longer a "G" filter to choose) so my original search is missing very many of the items I might want to have seen (for that, and no doubt other, brands)!
As others have said, the changes that ebay made last October have probably saved me money (buying a lot less) . . . but that's not necessarily good news for sellers.
Cheers
David