Some time ago I listened to a podcast from the Technical Marketing Handbook series from Simo Ahava, whose guest was Adam Halbardier from the Google Tag Manager product team. During the conversation, the topic of transparency of data handled by the Server-Side container appeared.
Facebook conversion tracking on the server side gives you oportunity to minimize usage of java script libraries on the client side and may reduce page load time. Running facebook conversion tracking codes on the server side may gives you better security for your clients data. You can have also more control over the data and decide which you want to send to facebook. Additional feature is that this solution minimizes the impact of ad blockers.
Implementation of Google Ads server side tracking has couple of advantages:
The standard, default Google Tag Manager implementation of GA4 is client side tracking. It means that client, in this situation: users browser like Google Chrome or Mozzila, is responsible for launching GTM/GA4 scripts and sending them to Google.