In terms of mobile phone model "OPPO-Reno5-Pro" and mobile phone "WeChat version 8.0.33",

That may be because when others read it, the other party has a personalized signature, while when you read it, the other party cancels the personalized signature.

Here's how to view the signatures of WeChat friends:

1. Open the mobile phone WeChat and click the address book.

2. Select a WeChat friend who wants to view the personalized signature.

3. On the WeChat friends homepage, click to enter the circle of friends.

Then, you can see each other's signature.

The above is the way to check the signature of WeChat.