PHP Fatal error: Uncaught Error: Call to undefined method stdClass::set()

WordPress version: 5.9
PHP version: 7.4.26

This is the Stack trace:

#0 /home/61dc8321c1ac18f874f6c789/public_html/wp-includes/class-wp-hook.php(309): WP_Hijri->posts_results_fl(Array)

#1 /home/61dc8321c1ac18f874f6c789/public_html/wp-includes/plugin.php(233): WP_Hook->apply_filters(Array, Array)

#2 /home/61dc8321c1ac18f874f6c789/public_html/wp-includes/class-wp-query.php(3131): apply_filters_ref_array('posts_results', Array)

#3 /home/61dc8321c1ac18f874f6c789/public_html/wp-includes/class-wp-query.php(3542): WP_Query->get_posts()

#4 /home/61dc8321c1ac18f874f6c789/public_html/wp-includes/post.php(2429): WP_Query->query(Array)

#5 /home/61dc8321c1ac18f874f6c789/public_html/wp-content/plugins/wpforms/includes/class-form.php(225): get_posts(Array)

#6 /home/61dc8321c1ac18f874f6c789/public_html/wp-content/plugins/wpforms/includes/class-form.php(138): WPForms_Form_Handler->get_multiple(Array)

#7 /home/61dc8321c1ac18f874f6c789/publi in /home/61dc8321c1ac18f874f6c789/public_html/wp-content/plugins/wp-hijri/main.php on line 319

Every fatal error has this extra fatal error also:

PHP Fatal error: Uncaught Error: Call to undefined method stdClass::is_feed() in /wp-includes/query.php:420

And here are the settings:
Hijri calendar algorithm: Um Al Qura algorithm (Recommended)
Language: WordPress Language
Other Options: Nothing selected
Date Format: Sat 18 Rajab 1443AH 19-2-2022AD

• This reply was modified 4 years, 3 months ago by Surbma.

As the lines already tell, it is WP Forms.

• This reply was modified 4 years, 2 months ago by Surbma.

This is the website, but the plugin is disabled, as it is generating the fatal error on the back-end:
https://productivemuslim.com

New version is installed. Generating no errors. Thank you!