I don't know what's wrong but some users switched to Laragon + Apache and it worked.
If you want to go with Nginx, you can try to increase the number of PHP Upstream Processes.
- Open user\laragon.ini (Menu > Laragon > Settings file: laragon.ini)
- Put Upstream=X under [nginx] section
Laragon will auto manage 5 PHP processes to handle requests.
Hope it help.