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: 7.4.7
wcf version: 1.0.11 pl 1 (Horizon)
date: Mon, 13 Jul 2020 18:54:09 +0000
request: /index.php?page=RGallery&rGalleryCat=none&reset_tag=1&s=9d625e4363e2a9d15b0a5243d542d14244f555a0
referer:

Stacktrace:

#0 /srv/www/vhosts/no-kill.de/httpdocs/lib/page/RGalleryPage.class.php(4): WCF::handleError(8192, 'Array and strin...', '/srv/www/vhosts...', 245, Array)
#1 /srv/www/vhosts/no-kill.de/httpdocs/lib/page/RGalleryPage.class.php(4): require_once()
#2 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/util/RequestHandler.class.php(57): require_once('/srv/www/vhosts...')
#3 /srv/www/vhosts/no-kill.de/httpdocs/wcf/lib/util/RequestHandler.class.php(91): RequestHandler->__construct('RGalleryPage', Array, 'page')
#4 /srv/www/vhosts/no-kill.de/httpdocs/index.php(8): RequestHandler::handle(Array)
#5 {main}