I have had this issue too and clearing cookies really helped. To clear cookies on iPhone, go to Settings , then Safari . Scroll down and tap Clear History and Website Data . This will clear cookies but will not affect your bookmarks or saved passwords. If you are concerned about keeping your personal information private, consider using privacy extensions. You can check out the article here
https://clearvpn.com/blog/how-to-clear-cookies-on-iphone/ and I hope it will help you a lot.