Feb 02 2021
If your users are seeing Teams preview features without being enabled for public preview channel then they most likely have custom app sideloading ON that allows them to switch to developer preview.
If above is not the case please reply below and we can investigate. Thank you!
Feb 05 2021
I have users seeing Preview Features, without being opted into the Preview. (not ticked) in their clicking. Ticking and unticking to enable/disable doesn't make a difference.
We had enabled "preview features" on the understanding it allowed users to choose wether to turn it on or off. I've now disabled in the hope that it fixes this nightmare.