Hi,
By default, the Browse by Subject page will include all "dc.subject.*" metadata fields. This is configured in the "webui.browse.index.*" settings in the dspace.cfg here:
If you'd like to ONLY include the "dc.subject" metadata field, then you should be able to do so by changing that setting to:
webui.browse.index.4 = subject:metadata:dc.subject:text
Then, you would need to perform a full reindex of the site, using "./dspace index-discovery -b".
For more information on these browse configuration settings, see the documentation at:
Tim