I don't have access to @typokign 's Helm chart repo so I forked the chart and put it up in a new Helm repo - https://arkaniad.github.io/matrix-chart/ hosted here
I also added a few fixes to allow running of more recent Synapse containers (I'm on 1.65 right now with no problems)
Getting a 404 from the helm repo ( https://dacruz21.github.io/helm-charts )