The last two updates (WW_17.1810.2010.179, WW_17.1810.2011.183) for me had no effect on the volume of the main speaker. So it's obviously not going to be a general problem that affects everyone. Are you sure this isn't a HW problem?
did not release the ZenFone 7 Pro no. only 7. people say there is no difference, but what is more important is the processor? so there is. as for the A11 I just updated it by the file available on the Asus website.