From Android 14 it is no longer possible to install any application that targets an API level below 23 - Android 6.0. 
Upon investigation, I've noticed a peculiar trend with other similar applications, such as [e.g. W2C] downloaded from itch io. These apps, which have a minimum SDK requirement significantly lower than the currently required SDK level of 23, are not using Android 14 as their target version. This suggests that there may be flexibility in the minimum SDK requirement for certain apps, depending on the targeted Android version and platform specifications.
I believe it depends on the engine, as normally they would need to support a vast number of devices, so they tend to cover the versions with more usage.
Your previous information was very valuable, as it led me to explore the code of the exporting Android target and I found out that indeed, the minimal SDK in the code is 21, so the default setting on the build is not matching with the actual code on the export.
But I can rebuild a custom export with the tweaked minimal SDK set to 24, so I’ll try that. Thank you for the test offer, I may take you up on that.