Been running it since August on an iPhone 7 with no problems. It did have problems in the early versions in July but they resolved quickly in later builds.
This is only semi-related but I thought I would throw it in. I've been using time lapse software for several years (LRTimelapse4) . They have since upgraded many times to a version LRTimelapse 5. The developer has told me that Catalina is not compatible with LR4. That,alone, will keep me from upgrading my iMAC to Catalina from Mojave.
A general observation. Catalina is a Very big update for Apple. I would wait until the .1 revision is released for any real time flight control system.
To add some helpful information.
iPhone pro MAX 256gig running current IOS and updates. No problems! Stock RC. Did just upgrade to SC, but the stock RC worked great with the new phone and software. New screen is bright too!