GZIP compression not working

Hello,

We have been experiencing this error here

gzip is not working properly:
- Your server may not have the "deflate" module enabled (mod_deflate for Apache, ngx_http_gzip_module for NGINX)
- Another plugin may be interfering with the configuration

Could you advise on how to proceed with it and have a look into the problem?
We disabled all plugins but didnt help