Hi @Jonathan Khan,
I'm sorry for the delay reply,
I see that a lot of users have the same issue as you are having. However, there hasn’t been an official announcement or fix from Microsoft yet.
I recommend encouraging affected end users to submit feedback and upvote existing feedback at Word · Community
As forum moderators, we don’t have access to the detailed logs or backend systems needed to troubleshoot this effectively due to privacy and security constraints. Our product team is in charge of the site, and they constantly check customer reviews and feedback, The higher votes, the more attention the related team will pay on. And a lot of features are developed and improved based on customer feedback.
How to Submit Your Suggestion to Microsoft:.
1.Visit the Microsoft Feedback Portal:
-Go to: Word · Community then Send Feedback and Describe your proposal in detail

Describe your suggestion clearly for example:
“The borders on tables in Microsoft Word keep disappearing when the file is share on a SharePoint site"
Alternatively you could also give feedback in Microsoft Word.
Go to Word select the option that I point out

Then select "Report a problem"
Thank you again for your time and understanding. Looking forward to your response!