In most cases, the crawling we do to check for broken links and mixed content does not add to your website visitor statistics.
If you use anything that measures your visitors on the client side, like Google Analytics, Simple Analytics, Fathom Analytics, ... the Oh Dear crawler will not count in your visitor stats.
Server-side initiated Google Analytics
Google Analytics has an API that allows you to send visitor statistics with server-side code. For instance, you could have PHP/Ruby/Perl send a Google Analytics event for every visitor that is detected on the site.
These will see the Oh Dear crawler and count our crawler as visitors.
Most of the plugins & tools used for server-side sending of Google Analytics events have a way to filter user-agents. This can be used to ignore our crawler by filtering our User-Agent.
If you use a server-side log parser, like Netlify's logs, Goaccess, AWStats, Webalizer, ..., you will see the Oh Dear crawler as one of the visitors.
Because those parsers look at the server logs to count visitors, we will be seen as one of those visitors.
The best course of action would be to exclude the Oh Dear IP addresses from the parsing software.