set of errors being logged from every page visited on site

I am getting a set of warning messages in my error log for every page visited on the website. This is happening whether I am logged in or not. The messages are:

PHP Warning: Undefined array key “js” in xxx\subscribe2\classes\class-s2-form-widget.php on line 116
PHP Warning: Undefined array key “nowrap” in xxx\subscribe2\classes\class-s2-form-widget.php on line 121
PHP Warning: Undefined array key “noantispam” in xxx\subscribe2\classes\class-s2-form-widget.php on line 122

I have checked with Subscribe2 as the only plugin active and Twenty Twenty-One theme and it is still happening.

Looking at the settings on the widget, it occurs when I have the three checkboxes at the bottom of the widget settings (js, nowrap and noantispam) not checked.

I am not sure whether it is related to the and I get an additional set of warnings (one for each of the above)::
PHP Deprecated: stripslashes(): Passing null to parameter #1 ($string) of type string is deprecated in xxx\subscribe2\classes\class-s2-form-widget.php on line 122

(and the same for lines 116 and 121)

I have just deleted off a 70MB error log from the website which was almost all this error. Please can you investigate?

Thanks