I cannot renew existing certificate from default CA (ZeroSSL)

[teksal]

I got certificate 3 months ago using --issue then --renew using manual mode (my DNS provider is not supported), verified via DNS TXT records, copied the related .cer and .key files (I run a custom Nodejs web server), all went well and my site worked successfully. I'm using default CA (which is ZeroSSL). Now I want to renew my cert because it expired today. I've run --renew, got new TXT string, changed the record in my DNS settings... basically I followed all the steps I did before (except --issue), running --renew again ended with Success, acme.sh --list shows the new extended dates, I copied the files as I did before, restarted my Nodejs server, but clients still see the old, expired certificate. I've repeated this several times, all ended in Success, no error, but clients do not see new extended certificate. What is the problem? How do I resolve this?

PS. I run a Debian VM instance on Google Cloud. I restarted the VM, even changed the public IP, the problem still persists. I attempted to login to ZeroSSL on their web site to see any info about my certificate, it always displays An error ocurred. Please try again.

[teksal]

I switched to Let's Encrypt.