Edits to Member Username & Screen Name fields result in errors

[mcfarlandonline]

EE versions 6.4.5 & 6.4.6
PHP 8.1.14

After registering a new member (Site Admin) from the CP, and attempting to update the user's Screen Name, I get this error message/screen:

Deprecated
strlen(): Passing null to parameter #1 ($string) of type string is deprecated
ee/ExpressionEngine/Service/Member/Member.php, line 89

Severity: E_DEPRECATED
Warning
Cannot modify header information - headers already sent by (output started at ee/legacy/core/Exceptions.php:120)
ee/legacy/core/Input.php, line 266

Severity: E_WARNING
Warning
Cannot modify header information - headers already sent by (output started at ee/legacy/core/Exceptions.php:120)
ee/legacy/libraries/Functions.php, line 458

Severity: E_WARNING

The updated Screen Name does save, but I have to Go Back in the browser to discover that.

I just tested the Username field on that page, and it also results in errors, but saves just fine.

I also tested updating the password for the member from that same Username & Password page, but it submitted just fine.

This was working for me in EE 6.4.4