Fatal error: PHP error in file /srv/www/vhosts/no-kill.de/httpdocs/lib/system/RGallerySystem.class.php (245): Array and string offset access syntax with curly braces is deprecated

Information:

error message: PHP error in file /srv/www/vhosts/no-kill.de/httpdocs/lib/system/RGallerySystem.class.php (245): Array and string offset access syntax with curly braces is deprecated
error code: 0
file: /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/system/WCF.class.php (255)
php version: 7.4.11
wcf version: 1.0.11 pl 1 (Horizon)
date: Wed, 28 Oct 2020 06:21:28 +0000
request: /index.php?page=User&userID=2&s=b01d84d1863a66081b3432abdc874fac1e1e8e5a
referer:

Stacktrace:

#0 /srv/www/vhosts/no-kill.de/httpdocs/lib/system/event/listener/RGalleryUserPageListener.class.php(3): WCF::handleError(8192, 'Array and strin...', '/srv/www/vhosts...', 245, Array)
#1 /srv/www/vhosts/no-kill.de/httpdocs/lib/system/event/listener/RGalleryUserPageListener.class.php(3): require_once()
#2 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/system/event/EventHandler.class.php(175): require_once('/srv/www/vhosts...')
#3 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/page/AbstractPage.class.php(63): EventHandler::fireAction(Object(UserPage), 'assignVariables')
#4 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/page/UserPage.class.php(105): AbstractPage->assignVariables()
#5 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/page/AbstractPage.class.php(77): UserPage->assignVariables()
#6 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/page/UserPage.class.php(170): AbstractPage->show()
#7 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/page/AbstractPage.class.php(36): UserPage->show()
#8 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/page/UserPage.class.php(37): AbstractPage->__construct()
#9 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/util/RequestHandler.class.php(63): UserPage->__construct()
#10 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/util/RequestHandler.class.php(91): RequestHandler->__construct('UserPage', Array, 'page')
#11 /srv/www/vhosts/no-kill.de/httpdocs/index.php(8): RequestHandler::handle(Array)
#12 {main}