FF doesn't really enable full fingerprint resistance by default. But it can.
These settings are some of what I usually use. All fingerprint values (that are able to be are randomised on every reload of a page.
Set secutity setting to custom, select known AND suspected fingerprinting > select from dropdown 'In ALL tabs'
Also: Because it's of no value / use to me, and (IMHO) a giant gaping privacy and security issue, I also disable webgl and webrtc, and navigator completely in about:config
Set the following:
WebGL webgl.disabled true
WebGL2 webgl.enable-webgl2 false
WebRTC media.peerconnection.enabled false
Navigator media.navigator.enabled false
RFP privacy.resistFingerprinting true
RFP options like bounce protection etc can also be enabled in config.
Check fingerprints on browserleaks.com, coveryourtracks.EFF.org, etc
Should be 100% unique fingerprint every time.