coming into this late and not sure how I missed it last week. No, I don't think it is too much to require them to clean up after themselves. If it is a new policy it is almost certain that it is because the gymnasts have been too messy. It shouldn't be taking that long for a team to clean the area so they are likely providing the rest of the time for transition which is fine with me.
I do not liken this to a restaurant, a service or a store, as others have. It is more like a school, where the children must throw away their snack/lunch garbage, clean up a spilled container, refilling the glue containers, put away lab materials, books, markers, crayons they used, and, in the olden days, clap out the erasers.
I understand that you are not happy that communication is poor and that can be a problem, unfortunately happens too often in gyms. But again, think of it like in a school - will a teacher communicate with you that she is now making the kids clean up? No - it is her job to run her class as she sees fit, as long as it is within acceptable parameters. We just don't think about it because we don't see it. Contrast that to the gym, where you can see it and therefore become upset by it. And, before someone comments about how much we pay for gym, where we don't for school - oh yes we do. It is just hidden in our taxes.
same for chalk - I don't know about your area but around here, families are given a list at the beginning of the school year demanding upwards of $100 worth of materials to be used communally - paper, folders, crayons, wipes, sanitizer, snacks, etc. Yes, parents complain but they all buy it. I see buying chalk (and tape) as no different. I personally would prefer that the gym include it in their gym/team fees so that the gym buys it at a discount but if the kids buy their own, they are more likely to be stingy about it versus the chalkbucket free reign.