So I upgraded my cluster to ES 8 a couple days ago...all is well mostly, but on the node doing the cluster monitoring, if I also upgrade Metricbeat to 8.0.0, then I almost immediately start getting weirdness showing up in Kibana - Elasticsearch version number suddenly goes into the hundreds and changes at random intervals, all nodes start going back and forth between showing as master or not, and probably other stuff I haven't noticed yet. Same thing happens on any other node i've tried so far.
If I downgrade back to 7.17.0 though, it works perfectly just as it always has.
Anyone else having this issue and/or know a possible solution?