TL;DR: Reddit is removing the option to opt out of ad personalization, targeting ads based on user activity. Some specific ad categories can still be limited, but there's no more opt-out option.
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For over the top action, but a Raspberry Pi with an ethernet port and install PiHole and change your router DNS to the IP address of the PiHole and bask in glory that 99.999% of the crap out there, will not come or go out of your household.