It’s likely the resist fingerprinting option. It breaks many websites or those that use bot checking thing.

The mods set it as the default for the subreddit in an attempt to combat brigading.

May not qualify as “simple” versus a VM, but you can try using chroot environment. You essentially run minimal Ubuntu environment from a folder that can be a newer or old version of the host OS.

Here is one guide to get up and running.

This guide is easier to follow IMO.