You are always going to see some jitter with cable. How bad it is depends on the utilisation of your node of the CMTS.
Your TBB chart looks similar to but maybe a bit better than mine following some work to fix bad oversubscription and although it isn't good there are plenty a lot worse. I was told that there would be no further work on mine unless the congestion got worse.
Here's one of mine from a day I didn't use the connection much. I mostly only speedtest at ~ 6:00 - 6:30am to see if there is upstream congestion even then - sometimes there is (the latency spike just after 6:00am will be caused by a speedtest).