The eMUTABLE_FLAGS you mentioned is an ENUM, which specifies, which flags are mutable, so it’s not related to my problem.
Writing directly to AndroidMainfest.xml is pointless, because the file is rewritten after each build.
I have read the document, which you posted even before posting my question here, on the forum, but other than helping me understand what PendingIntent really is, it didn’t help me solve my problem.
Thanks for trying though.