I'm wondering what the source for these apps were. Google Store downloads strip unnecessary localized assets at download time. This used to be a BIG deal back when icons were bitmaps; but compiled binaries do provide COMPLETE pre-rendered sets of bitmap icons if your downlevel minimum version (Android 5.0? Android 6.0?) extends that far. Which are then stripped whenever you download to modern phone. Assuming that you have SVG replacements for all legacy bitmap icons. Perhaps Gmail does not. So if there are multiple localizations, that would suggest that either the user is measuring the pre-installed app (which almost immediately upgraded and is therefore effectively replaced), or has obtained the APKs from a different source.

The publicly available email app in the Android sources is NOT gmail (and is therefore likely to be unloved and uncared for, and probaly will contain massive blobs of bitmap icons. So if it was that...

Any native code ALSO bloats compiled binary size dramatically (since binaries include code compiled for each processor you have selected when you performed the native build). Unnecessary binary blobs are stripped by the Play Store when you download. It is conceivable that gmail carries ancient crusty pieces of native code, I suppose, given its long heritage.

And also includes pre-compile maps to speed up startup. Very strange process. Apparently, the Google Play Store profiles the startup of the first 20-odd users who download your app, and then transmit the pre-compile map to all subsequent downloads. I'm not sure whether apps are pre-jitted at install time or whether the pre-jitted code is downloaded from the Play Store.(Play Store does tells you they are going to do it when you upload, and -- sure enough -- load time "magically" improves by a significant amount shortly after you push the binary to production. I don't honestly know whether pre-jitting has taken place before first load. (And whether that code shows up as cache space or app size).

Compat frameworks, on the other hand.... absolutely yes! I'm not sure that native Android framework code EVER gets executed on a modern app, to be honest. Almost all compat layers, and extensions, I think.