Thanks a lot to
@Biswajit , who gave me some key indications, now I have it working. Even though I'm not totally sure if the solution can bring problems in the future (*).
Seems to be that in the latest (at least, the latest that I could find)
Firebase SDK for Local Mac published in the forum, Crashlytics is a 4.0.0_beta version. On the other hand, Crashlytics should be at least 4.0.0+ so that everything works.
As a test, downloaded the latest SDK
HERE and just replaced the Crashlytics framework (only the arm64 version, for test purposes) in my Local Builder's Lib folder.
Immediately it worked.
(*) I guess that there can be implications by only changing one of the frameworks, since there can be dependencies/incompatibilities with others. In this case it worked, even though I must still check that Firebase notifications are still working and nothing is broken.
@Erel. Would it be possible to update at some moment the latest Firebase SDK for Local Mac?