Dear danielavizov,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
As per your description, we're sorry to hear that deselecting the Modern Comments under File > Options not working as expected in Word, and you don't like the design of modern comments and its update.
We do understand the inconvenience caused and apologize for it. To share your feedback directly with the product group, we'd recommend you navigate to Help > Feedback within Word, feedback submit by this way directly goes to the related team, this is the best way to let Word developers know your requirements and comments, help improve the product and make it better for you and others.
For your reference: How do I give feedback on Microsoft 365? - Microsoft Support
Please also consider sharing your feedback and voting for the similar ideas in Word Feedback Community (microsoft.com). The Product Team is in-charge of the feedback site, and they are constantly checking the comments and feedback from our customer. Many features have been developed or improved based on users' comment.
For the issue that deselect the Modern Comment not working as expected, we've done a quick test on Word in version 2310, deselect the Modern Comment and restart Word, and below attached is the screenshot of our test for your reference:

Given this, please check if updating the Office can help.
For your reference: Install Office updates - Microsoft Support
Please also try Online Repair to check if it can help.
For your reference: Repair an Office application - Microsoft Support
If the issue still persists, please share your Office information including the channel and subscription information by navigating to Word > File > Account and take a screenshot as shown below:
For your reference: About Office: What version of Office am I using? - Microsoft Support

Welcome to post back if any updates. We look forward to your reply.
If the understanding above is not consistent with yours, you can also post back and point that.
Sorry for the inconvenience again. Your patience and understanding are highly appreciated. Hope you stay safe and healthy.
Sincerely,
Rhoda | Microsoft Community Moderator