I have the DHCP approach working with my Samsung A20e Android11 phone.
I have the dhcp options defined on the DHCP Server WUI , as specified in the IPFire documentation.
On the Samsung Android phone I select the Proxy option to auro-config and then add the url for the proxy.pac file as here
http://ipfire.domain.org.:81/proxy.pac
For the Samsung phone I have it requires the proxy.pac file rather than the wpad.dat file. When I try to use the wpad.dat file the phone adds the .pac extension so the file ends up being wpad.dat.pac
Both the wpad.dat and proxy.pac point to the same file data.
With the proxy.pac file url the samsung phone was happy with that and the urls accessed can be seen in the IPFire WUI menu Logs - Proxy Logs.
Make sure you were not using an https url for the proxy.pac file as the IPFire wpad.dat and proxy.pac files are http urls.
My Samsung has an example entry for the PAC web address that uses https.
With the above I can see the Top Level Domain (TLD) browsing I was doing, in the Proxy Logs file, presuming that you have the Proxy Logging enabled.