I have the exact same problem.
A Chinese friend told me likely I posted something inappropriate and Wechat restricted me.
Not sure Wechat can influence my iphone settings but who knows.
I contacted wechat help desk and the answer was as follows:
Dear user, thanks for your feedback. We have checked and confirm that your WeChat account is working properly. If the function is restricted, please enter and follow the "WeChat Security Center" official account (WeChat ID:weixinsrc) , tap "I need" at the bottom left corner > tap "Query/unblock account function restrictions“ at the bottom of the list to query and unblock account functions and perform operations as prompted.
Gentle reminder: WeChat prohibits gifting, lending, transferring or otherwise permitting any other person to access or use your account. In addition, unauthorized use of third-party software, including but not limited to plug-ins, jailbreaking tools, virtual emulators, is prohibited. Please avoid frequently add friends or group chats in a short time, this may affect your account usage.
Please be sure to use the account in accordance with WeChat's policies. Thanks for your patience and continuous support.
So no fix from there, so I googled again and found this thread.
Is there any solution other than deleting and reinstalling the app? Could anybody else report if they got it fixed? I‘m scared to lose my conversations and contacts.
Any help is sincerely appreciated, I need wechat for work ☹️