I’m having the same issue with a Samsung Note 9 (and a Note 20 and a Tab A).
Last week I was getting issues opening the app very regularly, but with some good advice in the linked post managed to resolve some of the issues in the linked post. Android remote app doesn't work
About 20% of the time I still get stuck on the roon logo on startup - I reckon the android app is just a bit flaky and hasn’t been tested properly. They pretty much say as much on the website - https://help.roonlabs.com/portal/en/kb/articles/faq-what-android-devices-can-i-use-roon-with