Hello, ader274.
Thank you for posting in Apple Support Communities. We understand that you’re curious about whether using your MacBook Pro upside down in a vertical stand will cause longterm damage to your device.
Keeping in mind that Apple suggests using your MacBook on a hard, flat surface, like a table or desk for best temperature control, you shouldn’t see any longterm issues as long as the display is completely closed and there is no strain on any ports or cables that you have connected.
We encourage you to review the “Make sure the vents on your Apple product aren’t blocked” here:
About fans and fan noise in your Apple product - Apple Support
This article may also be helpful:
Use your Mac notebook computer in closed-display mode with an external display - Apple Support
Warmest Regards.