NotallyX OutOfMemory error

Hi everyone. I love this app and have used it continously for the last year. It's the first time it crashed out of the blue, while writing in a particular 45 kB note. I don't understand how this app's memory allocation works. 🤔 It was the only app open at the time and I know my phone has enough memory. Also, it's the first app that ever crashed due to such out of memory error. What do you guys think ?