403 error suddenly on Mautic instance after updating

Hello everyone.

I would like to inquire the following. I have the Mautic on my company which is very crucial part of our business.

However I had notification yesterday for update and once I updated I got this message 403 forbidden permission.

I saw posts for troubleshoot mentioning to remove some security lines on .htaccess.
I saw comment mentioned it is not advisable to remove due security measures. What is the best way from all aspects plus security for my machine to work normal again? Thanks very much!