After upgrading to PHP 8.0 and installing phpmyadmin using the official PPA, phpmyadmin would result in a blank page instead of a login. The apache2 error.log had several lines of :
Got error ‘PHP message: PHP Fatal error: Array and string offset access syntax with curly braces is no longer supported in /usr/share/php/tcpdf/tcpdf.php on line 16893’
The fix was to manually upgrade the php-tcpdf package:
sudo apt-get install php-tcpdf php-tcpdf