This seems to be an environmental issue. Please refer to the following KB and see if it resolves your issue:
https://www.appeon.com/developers/get-help/knowledgebase/4410

Additionally, we would like to know if you have already checked the following items. Are all of these items functioning normally?

*Check your Internet connection: Check your network cables, modem, and routers
*Check your DNS settings: If you're not sure what this means, contact your organization
*Allow PowerServer to access these addresses: https://apips.appeon.com/pslicense/, https://apips.appeon.net/pslicense/, https://apips2.appeon.com/pslicense/, https://apips2.appeon.net/pslicense/
*If you use a proxy server, check your proxy settings. You might need to ask your organization if the proxy server is working. If you don't think you should be using a proxy server, go to Settings > System > Open your computer's proxy settings
*If you use a debugging proxy server tool, for example, Fiddler and other software, please stop it and try again
*If the firewall or antivirus settings allow the access, try removing the relevant setting, and then adding it again.

It is particularly important to note item 4. If the machine connects to the Internet through a proxy server, make sure to configure the proxy server settings in the PowerServer Web APIs as well (UserConfig.json file > "ProxyOptions" block). The password for the proxy server (if any) must be an encrypted value (encrypted by the CustomizeDeploy.dll tool).

BTW, PowerServer 2021 is EOL, we suggest that you migrate to 2022 R3 at your earliest convenience.

Regards,

Tom