codecov upload step fails with a 404

Recently the codecov upload step on circleci started to fail like this:

Error: 400 Client Error: Bad Request for url: https://storage.googleapis.com/codecov/v4/raw/2020-05-28/3F10B6B6FEA878CCC9F58EAF87855DA8/ff95b772eb81755e7a88d23d84d8e2818d131475/23d1c1d0-7956-4e67-b810-25f0467807ef.txt?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=GOOG1EQX6OZVJGHKK3633AAFGLBUCOOATRACRQRQF6HMSMLYUP6EAD6XSWAAY%2F20200528%2FUS%2Fs3%2Faws4_request&X-Amz-Date=20200528T131649Z&X-Amz-Expires=10&X-Amz-SignedHeaders=host&X-Amz-Signature=4b40c9e5cfb14fdd66d7af8396cf048070c6e4d77c151e9dabc9f9b11ce88006

I assume they broke the old (pinned) client we're using. I almost filed an issue with them but part of their issue reporting guidelines are to switch to the "bash uploader" first. :/ So I guess they don't really care about the python uploader and we should switch to the bash uploader (which I have already confirmed fixes this issue).

And it only involves downloading a shell script from the internet during every build and then running it, what's the problem.