Release notes on the latest version of DoubleClick for Publishers show that Google has dropped support for Internet Explorer 10 and below on it’s Google Publisher Tags (GPT). Although the notice appears on the DFP Premium help, this change also effects DFP Small business.
GPT are the default tags now used by DFP, so this change impacts the tags used on most publisher sites.
According to Net Marketshare, IE 10 and below accounted for almost 3.6% of internet traffic last month. That is significant enough that some publishers will notice revenue impact. Actual browser marketshare varies significantly from one site to the next. OKO are advising that publishers check the browser report in analytics and consider the potential revenue impact of this change. If the potential impact is significant on a given website, script could be added to serve alternative ad code to users of old versions of Internet Explorer.
Browser version can be seen in Google Analytics by navigating to: Audience > Technology > Browser & OS and clicking through the Internet Explorer.
The release notes can be seen here on the DFP support site. The relevant section reads:
GPT no longer supporting IE version 10 or below
As of March 5, 2018, we no longer support ad serving with Google Publisher Tags (GPT) for Internet Explorer versions 10 and below. This may result in ads rendering incorrectly or failing to appear in these browsers, and impressions may not be counted.