I am having the same issue - I have an iPhone 12 Pro - with 53 GB storage available and is most up to date iOS 15.3.1. I also have this issue for the past few months. Every time I start to edit with the healing tool - the brush stroke freezes as a red dot on the screen and the app crashes. Can anyone assist with this?
Reviving an old thread about an old version is counter productive if you do not tell which version you use. The current version of Lightroom for iPhone is 7.2 and the healing tool works just fine for me with that version.