What I have observed is incremental smaller updates to Tor browser often leads to increase in Whonix storage space. This is strange behavior indeed as expected increase in OS space should be closer to at least such smaller updates. For example, assume the new browser update is 4 MB than corresponding Whonix size approximately grows by 40 times 4 MB to 160 MB.
I found this and repeated to be sure and results are almost same. Maybe an option to do a fresh install of Tor browser whenever required by fetching latest installer could help while wiping out remnants of the old?