Software update makes HDR content “unwatchable” on Roku TVs
Software update makes HDR content “unwatchable” on Roku TVs
arstechnica.com
Software update makes HDR content “unwatchable” on Roku TVs

Software update makes HDR content “unwatchable” on Roku TVs
Software update makes HDR content “unwatchable” on Roku TVs

A few days ago my TCL Roku TV got an update that offered (enabled by default) a new "Smart Picture" feature that supposedly obviates the need to set the picture mode manually. That seems like something worth investigating here.
https://community.roku.com/t5/Features-settings-updates/Roku-Smart-Picture-how-where-to-ask-ROKU-to-let-us-turn-this-quot-feature-quot-off/td-p/980373