It looks like that could be it. I saw the HardForkEncoderDisabledEra messages early on and decided simply to remove them from our view of the logfiles, mostly based on the not-very-much participation that happened here:
Just as we measured back then, our “stressed” relay today has 4x the HardForkEncoderDisabledEra bad connection reports as the “normal” one, which is a much greater disparity than the bad Tx. Interesting that also implies the nodes that didn’t upgrade before the “deadline” still haven’t upgraded today (after 1 month) and therefore maybe never will.
Though we can’t use it because our logging (SimpleView) is text-based, and the blocking script (BlockNodesViaFail2Ban.md) requires JSON, at least others are reporting that this workaround fixes the load problem. If needed I could rewrite the script to get the IP’s to ban from the SimpleView logfile.
But before doing that… there must be a reason why the new node still accepts connections from the pre-1.24.2 nodes. It would have been simple for the 1.24.2 nodes to drop those connections immediately, and if it weren’t doing anything at all with the old nodes then it wouldn’t lead to increased CPU and memory use. Therefore some information must still be transferred (enough to keep eating memory) which might serve some valid purpose… and if so, banning the old nodes would block that.
@_ilap has had some sensible things to say on similar subjects so I would ask if he has some insight about this.