hi, i switched from joomla 3 to joomla 4 and now i get these errors

Deprecated: Function strftime() is deprecated in /home/customer/www/yogafirenze.it/public_html/components/com_jevents/libraries/jevdate.php on line 276

Deprecated: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in /home/customer/www/yogafirenze.it/public_html/components/com_jevents/libraries/dbmodel.php on line 522

Deprecated: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in /home/customer/www/yogafirenze.it/public_html/components/com_jevents/libraries/dbmodel.php on line 522

Deprecated: Function strftime() is deprecated in /home/customer/www/yogafirenze.it/public_html/components/com_jevents/libraries/jevdate.php on line 276

Deprecated: htmlspecialchars(): Passing null to parameter #1 ($string) of type string is deprecated in /home/customer/www/yogafirenze.it/public_html/modules/mod_jevents_slideshow/tmpl/default/slideshow.php on line 43
Sorry there were no events found.

How can I solve the problem?

Thank you

url of my site
https://www.yogafirenze.it/