Based on your description, I understand that when you log in the site collection with a account, the account profile shows another account information.
Whether this issue occurs when you log in one site collection or all site collections?
Please try below tips to troubleshoot the issue.
1.Clear browser with passwords and other sign in data.
2.Log in the site collection with Incognito window, compare the result.
3.Log in the site collection in another browser, compare the result.
4.Log in the site collection with another account, compare the result.
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