PHPMyadmin broken, syntax error

This is ISPConfig 3.1.15p3 host, upgraded yesterday from Debian 9 to Debian 10. PHPMyAdmin is installed from buster-backports, version 4:4.9.7+dfsg1-1~bpo10+1. Originally host was installed as Debian 8 years ago. I checked with Perfect Server Guide for Buster and remembered to force reconfigure services.
Websites work and ISPConfig Panel is OK, but phpmyadmin does not start. It shows HTTP ERROR 500 and apache error log shows

Code:

PHP Parse error:  syntax error, unexpected 'const' (T_CONST), expecting variable (T_VARIABLE) in /usr/share/php/PhpMyAdmin/MoTranslator/Translator.php on line 58

I suspect phpmyadmin is running on PHP version older than PHP 7.1 . I do not know why this would be the case,

Code:

# update-alternatives --config php-cgi
There are 5 choices for the alternative php-cgi (providing /usr/bin/php-cgi).

  Selection    Path                 Priority   Status
------------------------------------------------------------
  0            /usr/bin/php-cgi7.3   73        auto mode
  1            /usr/bin/php-cgi5.6   56        manual mode
  2            /usr/bin/php-cgi7.0   70        manual mode
  3            /usr/bin/php-cgi7.2   72        manual mode
* 4            /usr/bin/php-cgi7.3   73        manual mode
  5            /usr/bin/php5-cgi     50        manual mode

Also --config php shows version 7.3.
But when I run the htf-common-issues.php it shows

Code:

##### VERSION CHECK #####

[INFO] php (cli) version is 7.3.25-1+0~20201130.73+debian10~1.gbp042074
[INFO] php-cgi (used for cgi php in default vhost!) is version 5.6.40-0+deb8u2

##### PORT CHECK #####

What is it that makes php-cgi still be PHP 5.6?

 

Web server is apache.
Several versions of mod-php:

Code:

# dpkg --list | grep libapache2-mod-php
ii  libapache2-mod-php                2:7.4+79+0~20201210.30+debian10~1.gbpedaf15                              all          server-side, HTML-embedded scripting language (Apache 2 module) (default)
ii  libapache2-mod-php5               5.6.40+dfsg-0+deb8u2                                                     amd64        server-side, HTML-embedded scripting language (Apache 2 module)
ii  libapache2-mod-php7.0             7.0.33-37+0~20201103.43+debian10~1.gbp25a3d7                             amd64        server-side, HTML-embedded scripting language (Apache 2 module)
ii  libapache2-mod-php7.2             7.2.34-8+0~20201103.52+debian10~1.gbpafa084                              amd64        server-side, HTML-embedded scripting language (Apache 2 module)
ii  libapache2-mod-php7.3             7.3.25-1+0~20201130.73+debian10~1.gbp042074                              amd64        server-side, HTML-embedded scripting language (Apache 2 module)
ii  libapache2-mod-php7.4             7.4.13-1+0~20201130.33+debian10~1.gbpd59941                              amd64        server-side, HTML-embedded scripting language (Apache 2 module)

Some of the websites on this host use PHP 5.6, so I try to keep 5.6 and just make phpmyamin use PHP 7.3 for example.

 

I do not know how to repair apache so it stops using the old PHP. I think it may have used PHP 5.6 the whole time host was running Debian 9 Stretch.

Code:

##### RUNNING SERVER PROCESSES #####

[INFO] I found the following web server(s):
        Unknown process (fcgi-pm) (PID 3213)

 

Got PHPMyAdmin working. What I did:

Code:

# a2dismod php7.0
# a2enmod php7.3
# systemctl restart apache2

It looks to me the upgrade process from Debian 9 to 10 does not handle PHP properly. Maybe it is on purpose that old PHP is kept running to not break existing applications. I must bug someone who knows PHP stuff to write about this in next Release Notes.
However, from htf_report

Code:

##### VERSION CHECK #####

[INFO] php (cli) version is 7.3.25-1+0~20201130.73+debian10~1.gbp042074
[INFO] php-cgi (used for cgi php in default vhost!) is version 5.6.40-0+deb8u2

##### PORT CHECK #####


##### MAIL SERVER CHECK #####


##### RUNNING SERVER PROCESSES #####

[INFO] I found the following web server(s):
        Apache 2 (PID 7649)

still shows php-cgi is 5.6. Where is this coming from?