Because I got onto a fork within a few hours of the update to 3.7.7.0, I looked at my peers for a possible source. As as of now, all but 2 are running 3.7.7.x. One is running 3.7.5.x. One is even running 3.6.3.x! I wish I could waive a magic wand and banish the last!
This really points to the need to suspend nodes running old versions from the network.
I tried to run my node with -banscore=20, not sure if it actually helped but technically it should.