CI4 - security with Forms

Hello,

I wonder a lot of things about security with my forms in Codeigniter 4. If someone could enlighten me... ^^

1 Is esc() function useful on Views or only in Controllers ?

2) Is esc() function (or something else) useful when sending an email ? (for preventing loading malware inside email maybe??) ?

3) Is it useful to enable 'csrf' with any form or a strong validation is enough ?

4) What kind of simple captcha would you recommend for bots ? I've tried to install ReCaptcha 3 and 2 without success because issues with Firefox and Apple Safari which doesn't allow loading such external ressource. It told me : "The source list for Content Security Policy directive 'script-src' contains an invalid source: ''strict-dynamic''. It will be ignored."

Thank you for your advices.

1. In views
2. I don't know, but I think no.
3. Both. CSRF and valitations to the all posts requisitions.