When using Solr as a search provider, search indexes are optimized after a rebuild even if the feature is disabled:
<setting name="ContentSearch.Solr.OptimizeOnRebuild.Enabled" value="false" />
To resolve the issue, consider one of the following options:
- Upgrade Sitecore XP instance to Sitecore XP 10.0 or later.
- For Sitecore XP 9.3, download and install the cumulative hotfix available at KB1001332.
- For Sitecore XP 9.0.1-9.0.2, download and install the patch found on this page:
Sitecore.Support.235313-9.0.1.0.zip