J4, CH7, TCPDF Error 500 on tcpdf.php:16901

Hi there,
​
I have website on Joomla! 4.2.3, PHP 8.1.11 and Chronoforms 7.
I need to use TCPDF, so I have there a TCPDF library too.
​
When I run my form, I get 500 error.
In a debug mode I got this:

Symfony\Component\ErrorHandler\Error\FatalError:
Compile Error: Array and string offset access syntax with curly braces is no longer supported

  at /www/plugins/system/chronog3_plg/chronog3/vendors/tcpdf/tcpdf.php:16901      

It is this part of code:
​

if (!empty($dom[$key]['value']) AND ($dom[$key]['value'][0] == 'h') AND (intval($dom[$key]['value']{1}) > 0) AND (intval($dom[$key]['value']{1}) < 7)) {

​
Would you be so kind and help me please to resolve it.
Thank you in advance.
​
Stefan

try this: https://github.com/tecnickcom/TCPDF/tags

Thank you rbock,
​
Would you be so kind and tell me what do you mean?
Install another TCPDF library?
Could you tell me how, please?
​
Thank you in advance,
Stefan

1. Download: https://github.com/tecnickcom/TCPDF/archive/refs/tags/6.5.0.tar.gz
2. Rename on Server: plugins/system/chronog3_plg/chronog3/vendors/tcpdf to plugins/system/chronog3_plg/chronog3/vendors/tcpdf_
3. Create Folder plugins/system/chronog3_plg/chronog3/vendors/tcpdf
4. Extract Files from 1. an copy to plugins/system/chronog3_plg/chronog3/vendors/tcpdf (config, fonts,etc.)
5. Copy Folder lang from plugins/system/chronog3_plg/chronog3/vendors/tcpdf/examples to plugins/system/chronog3_plg/chronog3/vendors/tcpdf/config