Php pdo_mysql is missing but active

Hello,
I made an fresh installation of Nextcloud.

How I get one Error Message:

PHP Startup: Unable to load dynamic library 'pdo_mysql' (tried: /usr/lib/php/20190902/pdo_mysql (/usr/lib/php/20190902/pdo_mysql: cannot open shared object file: No such file or directory), /usr/lib/php/20190902/pdo_mysql.so (/usr/lib/php/20190902/pdo_mysql.so: undefined symbol: mysqlnd_allocator)) at Unknown#0

It seems the php extension is not installed but it is.

php -m
Gives me

apcu
calendar
Core
ctype
curl
date
dom
exif
FFI
fileinfo
filter
ftp
gd
gettext
hash
iconv
imagick
intl
json
libxml
mbstring
mysqli
mysqlnd
openssl
pcntl
pcre
PDO
pdo_mysql
Phar
posix
readline
Reflection
session
shmop
SimpleXML
sockets
sodium
SPL
standard
sysvmsg
sysvsem
sysvshm
tokenizer
xml
xmlreader
xmlwriter
xsl
Zend OPcache
zip
zlib

[Zend Modules]
Zend OPcache```

No error Message with php -v

```PHP 7.4.3 (cli) (built: Oct  6 2020 15:47:56) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.3, Copyright (c), by Zend Technologies```

What's happen here?

What is this meaning? 


usr/lib/php/20190902/pdo_mysql.so: undefined symbol: mysqlnd_allocator


Version:

Ubuntu 20.04.1 LTS
Nextcloud 20.01
Php 7.4
Mysql