Storing cached temporary decrypted files

Are the files stored unencrypted for some time? For example, if you need to open them through a third-party application, since Cryptomator does not have a built-in viewer? It’s just that I saw on the forum that when decrypting, the data is actually saved in plain text so that other programs can use it. I wonder how this is implemented on Android/iOS mobile devices, as well as on PCs.