Is there a firewall for OpenLiteSpeed(beta) ?
If i install OpenLiteSpeed(beta) is it more vulnerable than installing nginx, since there is a firewall plugin for nginx?

No it isnt.
You can use Cloudflare as WAF.
I dont used much LiteSpeed in aapanel, but you can use mod_security, if available.
When i used it, i failed to use litespeed web panel. dont know if it is wanted so, but i dont got it working

I think the nginx waf addon is not doing more than Cloudflare

    i dont recommend using OLS for live site its still under testing and beta

    2 months later