chinese character & weird diamond question mark

I have searched through previous posts and tried the methods posted, but it didn’t work for me, so please kindly take a look at the problem i am facing. tks in advance!

1. Chinese Characters becoming ???
I imported my previous posts from blogger. The original posts are still there. But when imported, the chinese characters became ???
you can see the original and imported posts from the following link:
a. original post https://victoriachan1.blogspot.com/2006/10/placentafor-what.html
b. imported post
https://www.chanlegacy.com/2006/10/14/placentafor-what/

As suggested in other similar posts, I went to wp-config.php and deleted the 2 lines
define(‘DB_CHARSET’, ‘utf8’);
define(‘DB_COLLATE’, ”);

It didn’t work, the ??? are still ???, but now it led to another problem as stated in no.2.

How can I solve this issue? Has this got to do with the posts being imported from blogger? But when I try to create new wordpress posts with some chinese characters, it also becomes ??? when published. Or has it got to do with the language installation?

2. Weird Question Mark in Black Diamond
The moment i deleted the above 2 lines from wp-config.php, and went to my home page https://www.chanlegacy.com, 5 out of 10 of the posts in the home page has this weird question mark in black diamond thingy, it does not replace any quotation mark, but only appear in places where I “spaced bar”.

It only affects 5 of my 10 posts on the home page, subsequent pages or previous posts are not affected.

How do I get rid of the weird mark?

Kindly help me with the above 2 issues. Greatly Appreciate it!