Error:
“ParseError: syntax error, unexpected ‘|’ , expecting ‘;’ or ‘{‘ in Composer\Autoload\{closure}() (line 76 of modules/contrib/content_export_csv/src/ContentExport.php).”

The issue is related to the PHP version and the module in question.
In this case: content_export_csv. The Union Types “: int|array” caused the issue and it is not supported by your PHP version.

Here the line 76 referenced that is giving the error:
"public function getNodeIds(string $nodeType, int $status = 1) : int|array {"

In my case, I simply removed it and I was able to use the module on PHP7.4.
The function now becomes:
“public function getNodeIds(string $nodeType, int $status = 1) {“

If you are getting this error while trying to install Microsoft Drivers for PHP for SQL server

sudo pecl install sqlsrv 
sudo pecl install pdo_sqlsrv

you should do the following:

First:

Inspect this folder /usr/lib/x86_64-linux-gnu/ and verify that the following file exists: libltdl.la

Second:

If the file does not exist, just run the following command to create a blank file:

touch /usr/lib/x86_64-linux-gnu/libltdl.la

Try to run the pecl command again

sudo pecl install sqlsrv
sudo pecl install pdo_sqlsrv

Third:

If the issue still persists, create a new file and copy the following content to it:
https://www.apt-browse.org/browse/debian/jessie/main/amd64/libltdl-dev/2.4.2-1.11+b1/file/usr/lib/x86_64-linux-gnu/libltdl.la
and try to install the sqlsrv and pdo_sqlsrv again.
then verify that you can see the pdo_sqlsrv module by running:

php -m

Reference
Linux and macOS Installation Tutorial for the Microsoft Drivers for PHP for SQL Server

Install the Microsoft ODBC driver for SQL Server (Linux)