I reported them to THS and this was their response: "We appreciate you bringing this to our attention. Technically, the pet parent is allowed to ask for assistance from a sitter for utility expenses to help out with the cost. However, it will be a risk for them as they may not be able to find a sitter who will apply for their sit.
This usually only happens on longer sits, but the pet parents can request it for any length or sit, as long as they are upfront and transparent about it on the listing and in their first contact messages with the sitters. Trustedhousesitters will not be involved in any of these arrangements; this is a private arrangement, and all agreements are directly between the sitters and the pet parents. "