I have checked code of codeshare.io/2jJLDK and found the issue. Please follow below instructions for fix this issue.
In the form function, you have used input type as “url” for Link and as per rule of input type “url”, it can’t take “#” so you must use actual url with http/https like https://www.google.com/ for saving/updating widget link data.*
If you want to save/update widget link data with “#” then you need to change input type as “text” like below
From:
<input type="url" name="<?php echo esc_attr( $this->get_field_name( 'link' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'link' ) ); ?>" class="widefat" value="<?php echo esc_attr( $link ) ?>">
To:
<input type="text" name="<?php echo esc_attr( $this->get_field_name( 'link' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'link' ) ); ?>" class="widefat" value="<?php echo esc_attr( $link ) ?>">