I have no recollection of ever interacting with you before, so why are you repeatedly implying I'm a cheap freeloader? I really don't know what your problem is, but seriously you're way out of line. Do you work for Uptimerobot or something?
Not that it's any of your business, but I signed up for Uptimerobot only barely two months prior to receiving this email about the free plan change. I was using it as a secondary/auxiliary uptime monitoring service for my bootstrapped business, to supplement my primary monitoring. In that brief time, I had no actual outages, but Uptimerobot did have one false positive outage report where they claimed my site was down when it wasn't. So my overall impression of their service was already "need more time to see if this is worth paying for".
Upon then receiving notice that they would be terminating the free plan during Thanksgiving weekend with less than a month of notice, my impression changed to "never ever trust this service for anything". If they had instead offered a more reasonable time period, I would have seriously considered switching to a paid plan, assuming there were no further repeats of their false positive alerts.
I was only using Uptimerobot to monitor 2 sites, which means they were sending less than 600 tiny HEAD requests to my infra per day. The approximate cost of that to them should easily be less than one cent per month.
fwiw, my own product has a free version which has been downloaded over 2 million times and is used by several thousand companies, including some of the largest companies in the world who nonetheless pay me nothing. Despite that, there is no conceivable situation in which I would discontinue a free product with only 26 days notice, as that just pisses off users, flushes reputation down the toilet, and is completely counterproductive to improving revenue.