I would try deactivating them all (apart from Wordfence), and see if this stops the ads. If so, then it's a case of reactivating them one by on until you locate the problem plugin. I notice that at least one of your plugins (Limit Login Attempts) hasn't been updated in over two years, and Wordfence offers exactly the same functionality. It's a good practice to reduce the number of plugins that are installed wherever possible (consider each one as an additional door that can lead into your site), and only use those that are regularly updated by the authors.
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