All form stopped working

Hi, please, can you help how to detect the problem with all Contact-form-7 forms?

All forms on our website stopped working. If I try to send it, the error will raise:

https://www.skolasykorka.cz/wp-json/contact-form-7/v1/contact-forms/3444/feedback?_locale=user

code: “internal_server_error”
data: {status: 500}
message: “<p>There has been a critical error on this website.</p><p>Learn more about troubleshooting WordPress.</p>”

In Chrome console, there is:

api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2 POST https://www.skolasykorka.cz/wp-json/contact-form-7/v1/contact-forms/3444/feedback?_locale=user 500
F @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
tryCatch @ wp-polyfill.min.js?ver=7.4.4:1
invoke @ wp-polyfill.min.js?ver=7.4.4:1
t.<computed> @ wp-polyfill.min.js?ver=7.4.4:1
n @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
a @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
I @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
f @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
I @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
f @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
t @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
R @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ index.js?ver=5.4:1
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
(anonymous) @ index.js?ver=5.4:1
(anonymous) @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
X @ api-fetch.min.js?ver=a783d1f442d2abefc7d6dbd156a44561:2
f @ index.js?ver=5.4:1
(anonymous) @ index.js?ver=5.4:1
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Other plugins on our site:

Contact Form 7
Duplikovat stránku
Export media with selected content
Fast Gallery for Visual Composer
Flamingo
Google Analytics for WordPress by MonsterInsights
Header and Footer Scripts
Loco Translate
Zvolit: Max upload size	
MNKY | Visual Composer Pricing Boxes
Newsletter
Redirection
Responsive Lightbox & Gallery
Restricted Site Access
Simple Custom Post Order
Slider Revolution
Timetable Responsive Schedule For WordPress
Vlastní obsah
WooCommerce
WP Config File Editor
WP Statistiky
WPBakery Page Builder

Thanks a lot – it’s very important to have it working!

Tomas

The page I need help with: [log in to see the link]