Googled it, and some interesting reading popped up: you may like to look at this one below as a starter.
https://ww.wp.xz.cn/support/topic/notice-wpcf7_remove_shortcode-is-deprecated/
The general consensus from a quick scan, is that it may well be another mailer plugin that’s causing it, and not CF& at all.
As I say, it may or may not help you.
Thanks Mrs,
I’ve checked that link and I’ve noticed was the datepicker creating the issues. I edited the date.php file like it says in that topic and the error message disappeared, non completely though.
Now fortunately the website and contact form are loading properly with the plugin active but on top of the contact for a error is been shown:
Notice: WPCF7_Shortcode is deprecated since Contact Form 7 version 4.6! Use WPCF7_FormTag instead. in /home/prontoitaliano/public_html/wp-content/plugins/contact-form-7/includes/functions.php on line 374
Ok solution found, thanks to the first step.
The contact form 7 developer stopped to use the name shortcode in their code
They renamed this because the use of the term “shortcode” was confusing. It is actually a form-tag of the Contact Form 7 plugin, but sounds like a shortcode of WordPress itself. Those two concepts are similar, but fundamentally different.
Why my issue came up? Because other add ons plugin made from third parties didn’t update their codes, so what I had to do was replacing all the these tags (in my case in the datepicker – date.php):
WPCF7_Shortcode
WPCF7_ShortcodeManager
wpcf7_add_shortcode()
wpcf7_scan_shortcode())
whith these:
WPCF7_FormTag
WPCF7_FormTagsManager
wpcf7_add_form_tag()
pcf7_scan_form_tags()
Hope it helps!