In the current version of the app, overriding lifecycle hook such as ngOnDestroy is not working as expected. It is possible that this broke during the upgrade to Ionic 5, but we didn't notice until now.

Doing some tests I've asserted that the problem originates from the way we're declaring the lifecycle hooks, which is overriding them at runtime. This is something that may have changed in newer versions of Angular, given that these hooks are dependant on implementing a Typescript interface which shouldn't have any bearing at runtime but is used by Angular's compilation process.