It worked the same as on the 2018 model up until around December of last year.I wish I seen how well this worked.
I only owned this tv since January and by that time the 4k HDR video files from an external hdd, never worked. They did work fine on the TCL 6 2018 model, so I always wish tcl would fix this again. On the older TCL 6, the videos looked brighter and sharper playing thru the Roku tv app rather than another device like a HTPC or shield TV or firetv. The built in Roku app always had brighter and sharper HDR pop. HDR from our own hdd files looked comparable in quality to Dolby vision content from Netflix, and Disney plus apps.