How suggestion works?

You must click Publish or Save Draft on the page or post for any Multicollab activity to save on your website database. There is currently no autosave feature for Multicollab.
You can use Suggestion Mode to manage the editorial process of content creation and collaboratively navigate through editorial workflows and troubleshooting within WordPress.
Just like Google Docs suggesting mode, you can suggest changes to a post without changing the original text. When Suggestion Mode is enabled, any changes to this post will be highlighted to review by the post’s author and other authorized collaborators.

How to Use The Suggestion Feature

To use Suggestion Mode, the Admin user must have turned on Suggestions within the Multicollab settings menu (Admin Dashboard > Multicollab > Settings > Suggestion Mode). The Admin can turn suggestions on for all pages, specific pages or posts, or specific categories.
On Administrator-approved pages or posts, authors can toggle Suggestion Mode on or off. This is done by clicking on the Multicollab icon in the top right corner of the editing screen and clicking on the Settings tab (⚙️), and enabling Suggest Edits.
Authorized users can accept, reject and comment on each suggestion directly within WordPress. Depending on the Administrator’s settings, suggestions can trigger automated alerts sent via also trigger automated alerts sent via automated email notifications and/or Slack notifications.

Color-coded By Contributor

Suggestions on posts or pages are color-coded by each contributor to that page or post. To enhance organization, one contributor’s suggestions appear in the same color throughout a page or post to scan the editorial workspace within Gutenberg Editor quickly.
Suggestion mode only works with specific blocks at this moment. Check this for compatibility and limitation of the suggestion feature.