It’s not against the rules. Although Roblox reserves the right to take action on any situation (see Appendix A), it is highly unlikely that they would do so. There is absolutely nothing that prohibits that. The only false advertising statutes regarding user-generated content on Roblox (see Appendix B) do not apply to you in this situation; not only are you truthfully representing your product, you’re likely not making and running an advertisement for that specific game pass.
Furthermore, anyone who buys your game pass and had a problem with the result would likely not submit a report (or, perhaps, would simply report the game or game pass, which isn’t a very effective option in this case), but would simply be angry about their lost Robux for a while and move on.
EDIT: Going off of what @colbert2677 said, be extremely cautious to not misrepresent the game pass. Let the disclaimer be more noticeable than the joke “VIP” text. As he said, it may indeed be a good idea to create a mock version of the purchase and have the donation pass elsewhere. The less of a chance there is of moderation, the better of you are.
Appendix A (The right of Roblox to resolve issues between game developers and payors)
“If you have any problems or concerns with Dev Game Services or Dev Game Item Services, you should contact the Dev of the Dev Game Services or Dev Game Item Services to resolve the issue. Although we are not responsible for any such issues, we have an interest in making sure that we keep the Service a good experience for all involved. As such, we reserve the right, in our sole discretion, to intervene in and assist in attempting to resolve issues between Devs and Payors. To escalate any such problem to us, please first make a good faith attempt to work out a solution with the Dev. After such a good faith attempt, you may escalate to our Customer Service department completing the Customer Support Form (Support - Roblox). If we choose to take action, Devs and Payors agree that our decision (which may include deducting Robux from the Dev and crediting of Robux to the Payor) is final and Devs and Payors shall abide by that decision. You agree to work with us in a timely manner to resolve all such issues, and failure to do so is considered a violation of these Terms.”
Roblox Terms of Service § 5(C)(1)
Appendix B (Statutes regarding false advertisement)
- “Clickbait” advertisements are not permitted. Advertisements such as “Click this 1000 times”, “Click to pick your Dominus” or ones that offer free Robux, Roblox virtual items, etc. or that otherwise falsely represent the content being advertised and solely exist to encourage a user to click on the ad to inflate ad clicks are not permitted.
Excerpt from Roblox Community Rules § II.3
- Ads cannot falsely represent the content being advertised to encourage user engagement (e.g., offer free Robux).
Excerpt from Roblox Community Rules § II.4