Just to verify... It is the BBEdit Editor Defaults Settings panel where you have the "Auto-expand tabs" option checked?
If so, I've checked both BBEdit version 15.5.5 (15C124, Apple Silicon) running on macOS 15.7.7 and BBEdit version 16.0.1 (16A58, Apple Silicon) running on macOS Tahoe 26.5 and "Edit -> Normalize Options" when the dialog's "Normalize" button is clicked does normalize the front file window's Text Options sheet (the gear icon's sheet) settings to match the settings in the BBEdit Editor Defaults Settings panel.
I've tried quite a few variations; however, I can't find a combination that duplicates the behavior you're describing. I've tried:
1. Editor Defaults - Auto-expand tabs - ON; file window Text Options - Auto-expand tabs - OFF; after "Edit -> Normalize Options" file window Text Options - Auto-expand tabs - ON
2. The opposite; Editor Defaults - Auto-expand tabs - OFF; file window Text Options - Auto-expand tabs - ON; after "Edit -> Normalize Options" file window Text Options - Auto-expand tabs - OFF
That's the expected behavior of "Edit -> Normalize Options".
If you close a file/window that "Edit -> Normalize Options" has been applied to, then change a BBEdit Editor Defaults Settings panel setting; then reopen the closed file, the file window's Text Options sheet will have the setting set to match what the BBEdit Editor Defaults Settings panel current settings are and not what they were when the file was last closed when in the "Edit -> Normalize Options" state. However, if any manual change has been made to the file window's Text Options sheet before closing, reopening the file just tracks the previous manually changed state.