Hi swissbird,
In many apps, you can simply touch and hold the address to see a selection of actions. Instead of a quick tap, try to touch the address and firmly hold your finger on the screen for about 3 seconds. Do you see an overlay with an option to either Open in Maps or Copy address?
If not, you might reach out to Meta support directly. They'll be the experts when it comes to the Messenger app.
How to contact an app developer will show you how to reach out.
Contact the developer of an iOS, iPadOS, or watchOS app
1. Open the App Store on your iPhone or iPad.
2. Search for the app, then tap it. If you can't find it, tap the account button or your photo at the top of the screen, tap Purchased, tap "Not on this [device]," then tap the app.
3. The app's product page appears. Scroll to the Ratings & Reviews section, then tap App Support. If you don't see App Support, make sure that you're signed in with the correct Apple ID.
Thank you for being part of the Apple Support Communities.
Kindest Regards.