It appears that eBay has recently changed the way that search corrections are handled, and this may have caused some saved searches to no longer work correctly.
I do not think the issue is related to the app at all; you may actually find it easier to correct this using a browser, preferably a desktop browser.
Often when a search keyword provides few matches, but a slight variation in that keyword produces many results, eBay may substitute the more popular keyword directly. This can be very handy if the user has made a typo, but in some cases the substitute keyword is not what the user is searching for at all.
Using a desktop browser, when such a search substitution is done, there should be a message at the top of the search results alerting the user of the substitution, with a link to the original search without the substitution.
The app may have a similar message. If you follow that highlighted link, you should get the original search. Using a desktop browser it is relatively easy to open the saved search results in a new tab, unsave the old search, follow the highlighted link to the original "as intended" search, then save the new search. From then on, when that saved search is used, there should be no substitutions.
Alternatively, you can force eBay to search for your literal keywords with no substitutions or category changes by putting any one of your search keywords in quotes.
