Failed to register App when running from local due to SSL error

This seems to be related to SSL Error while installing addon - #5 by piotr.patrzek1. But that thread said it was solved and it did not include the client-side error. So I created this new topic.

When I use the official Atlassian Connect Express to register an APP, there is a big chance (> 50%) that it errors out with the following error (note the highlighted subcode: ump.pluginInstall.error.ssl line):

Failed to register with host https://zenuml-stg.atlassian.net/wiki (200)
{"type":"INSTALL","pingAfter":300,"status":{"done":true,"statusCode":200,"contentType":"application/vnd.atl.plugins.task.install.err+json",

**"subCode":"upm.pluginInstall.error.ssl"**,

"source":"https://air.zenuml.com/atlassian-connect.json","name":"https://air.zenuml.com/atlassian-connect.json"},"links":{"self":"/wiki/rest/plugins/1.0/pending/e3789319-ea75-4c9b-83fa-29590926c998","alternate":"/wiki/rest/plugins/1.0/tasks/e3789319-ea75-4c9b-83fa-29590926c998"},"timestamp":1617797921094,"accountId":"557058:0a2e245b-f5cd-42f7-bf07-a53b8d17e94f","id":"e3789319-ea75-4c9b-83fa-29590926c998"}
Add-on not registered; no compatible hosts detected

It normally works if I kill it and rerun. I am using cloudflare’s argo tunnel to expose my local service. ( Argo Tunnel | Secure Tunneling Software | Cloudflare). I used this command to start the local service: AC_LOCAL_BASE_URL=https://air.zenuml.com node -r esm app.js, where air.zenuml.com is my public hosting name.

I have no idea what I should check as it is not 100% reproducible. Can someone please help?

By the way, when I install it manually from the ump page, I also see this error often.