Just for the records. During the last five years we had this two directives in our apache2 reverse proxy setup:
- SetOutputFilter proxy-html
- RequestHeader unset Accept-Encoding
This worked till the upgrade to 12.3. To avoid the encoding error, I removed this settings and everything works as expected.
I know that I have added this to directives to avoid an encoding problem in an old version.
May be this information useful for others.