OK. After some research, I've found the reason.
Gnome applications like Evolution use gsettings to control various things, and I had a suspicion that one of them might be involved. I couldn't find maximized-by-default which is usually a prime culprit, but I did find org.gnome.mutter:
$ gsettings list-keys org.gnome.mutter
attach-modal-dialogs
auto-maximize
center-new-windows
check-alive-timeout
draggable-border-width
dynamic-workspaces
edge-tiling
experimental-features
focus-change-on-pointer-rest
locate-pointer-key
no-tab-popup
overlay-key
workspaces-only-on-primary
The auto-maximize looked promising.
$ gsettings get org.gnome.mutter auto-maximize
true
Ah. Try turning it off:
$ gsettings set org.gnome.mutter auto-maximize false
Now went back and tried restoring, closing and restarting Brave and Evolution. This time their windows correctly restarted in restored state.
I'm documenting this here so if anybody else runs into the same issue then hopefully it is a solution. The only curious point is whether the org.gnome.mutter came with Zorin by default or it got added as part of any subsequent updates and installations.
Thanks for your help though, Ponce-De-Leon. At least switching to XOrg has actually fixed some other annoyances I had with Zorin. 