Google published on their data anomalies page about a new error in the reporting section of the old Google Search Console’s blocked resources report. You may see decreased counts of pages with blocked resources. The report will be fixed going forward but you should be aware that there was a reporting glitch between the days of January 16 – February 22, 2018.

Google wrote:

You should also see a “note” line in the report, indicating the issue:

Just an FYI if you missed this note.

Forum discussion at Twitter.