I don't want to armchair ops your decisions, but maybe do consider moving to some dedicated Hetzner servers, at least for the runners. You can probably reduce that cost tenfold relatively simply.
Problem is Hetzner has such stringent user verification its tough to get hosting on there.
You don't even need to use Hetzner, I'm actually quite surprised they are spending 2k on DB. For the env isolation i understand they need ec2 but...
it shouldn't cost anywhere that amount, for instance I have 3 million users on a $40/month digital ocean VPS with just Django + Postgres and I have far more reads and writes.
for env isolation you could spin up a $5/month VPS and shut it down when idle