WinMTR was performed in reverse and nothing in that magnitude could be detected. I see some delays occasionally but nothing that can be visible nor within seconds like that. Those are mostly packets in the range of 100 to 200 ms, which is normal, during a constant communication, based on all the traffic over the Internet.

There is also no support ticket at the ISP level for such situation for yesterday.

Please, note that there was two updates yesterday and those could trigger a small wait time between 10 and 12 seconds on the first hit(s) the time it takes to reload a bunch of stuff in memory. If this would happen at the same time, this could have caused such behavior. But, nothing like that would last for several minutes nor occuring at several times during the day.

My best guess is simply something along the Internet. When I looked at the Worst column of your WinMTR result, this is probably the cause.