NEED TO FIX WEBSITE: Fatal error: Namespace declaration statement has to be the very first statement or after any declare call in the script

Hi guys, I run on my own pocket, so I don't have much money to pay, but I am willing to find the best price as soon as we solve this problem. I guess once (atleast once) in 24 hours I get error as described bellow. I have tried to delete the plugin which shows error, but I think something causes to re-write the php files of the plugins, cause the same problem appears almost to all plugins. "Fatal error: Namespace declaration statement has to be the very first statement or after any declare call in the script in /home/website/public_html/wp-content/plugins/addons-for-elementor-pro/[login to view URL] on line 28" at the line 28 there is a "namespace Livemesh Addons;" I can fix this only when I restore backup using softaculous, but I know for sure that in the next 24 hours this will happen again anyway. All help and hint are welcome. P.S., I use Litespeed cache, Cloudflare. WP version is the latest 4.9.4, php version is 7.2. P.P.S., I have another WP website also with Litespeed, Cloudflare and the same WP and PHP versions, but it seems that it runs ok...