I had the same issue with my WordPress website, I had installed it on Google Cloud, and by default, the Application installed pagespeed mod for apache. But I found the solution on the Bitnami documentation page.
Check If PageSpeed Is Enabled
execute the command or edit conf file using FTP:
nano /opt/bitnami/apache2/conf/httpd.conf
And if you find these two lines:
Include conf/pagespeed.conf
Include conf/pagespeed_libraries.conf
That means pagespeed mod is enabled.
For Disable PageSpeed
execute the same command or edit conf file using FTP:
nano /opt/bitnami/apache2/conf/httpd.conf
Comment out the following lines as below:
#Include conf/pagespeed.conf
#Include conf/pagespeed_libraries.conf
Now restart the apache server
sudo /opt/bitnami/ctlscript.sh restart apache
Note:-
As above mentioned, the command and the directory location would be changed depending on the Apache server location or your deployment application.
For a detailed article, check out the official Bitnami WordPress Documentation.