Everyone want to play against better players but i think it is possible to become better when playing worse players aswell. I find that many just do not take responsible for they own development. You do, since you ask the question.
Of course if the level gap is to big it is very hard.
Play softer so they can take the ball, and it become good play. As long as you do the correct stroke/motion you will benefit from this. Almost better to play with worse players and have the time to really do the correct stroke than with better and do not have the time. But of couse it can be hard to play to soft and do the correct stroke. So it is excellent working on the technique with worse players.
Do some multiball. If you play soft in exercise you can do multiball and there you can play harder and much tougher. I have a hard time seeing that they can not do multiball if they practice it a little more.
Change the drill. make it as hard as possible for you and as easy as possible for them. Like you put eveything against there best ball and they pu the ball free. The same if you block. Worse players also spread the ball all over the place so it is good practice that you need to move sidway and back and forth. And do exercises where you get play. Avoid serve and return if you are much better.
Do shadow training, physical exercise at the table or serve training. Alot of stuff you can work at alone. A good serve will win you alot more games.
Like someone else said,maybe you can help them. Blocking topspin is not difficult, just teach them how.
If you think about it i think you can come up with different ways to get something out of the practice.
Regarding the serve returns, it is difficult if you do not practice against people with spin in their serve. I think if you really understand how to read spin and how to return these, maybe you still can return the good. If your training partners can get some spin maybe you can color the ball to learn to read spin then trying different ways to return it, push, flip, go with and against the spin. Again, maybe you can teach them some serves.
I almost never practice against better players, but the level gap is not huge. As long as they have a somewhat good block i can do the above to get something out of it. As a coach i see to many players waste their time because they do not try against worse players. I think the biggest problem is not playing soft enough and not changing the drill. I have also seen as a coach that players that always play with better players become better, but they have harder to learn the correct strokes because the tempo is to high.
Maybe you can film a practice. It is hard to give advice when we do not know how big the level gap really is. Good luck!