Until the official "Solution" is something other than an effectively empty promise that the people in charge will consider the issue, try the following:
https://community.roku.com/t5/Suggest-a-Feature/Please-Remove-Home-Screen-Ads-Previews-for-Restricte...
I can confirm that this still works as of December 2022. There's some other useful information in the associated thread; be sure to "kudos" the resourceful individual who found this solution.
Yes! This is the ad that got me searching for controls. NOTHING!! This is completely inappropriate for my 11 and 9 year old sons to see constantly!!!
Roku is prioritizing ad revenue over the safety of young children with inappropriate ads. I'm switching. Who can make a recommendation for a family friendly platform?
There is something that can be done about obscene, indecent and profane broadcasts (including commercials, ads, etc.) This is right off of the FCC website. Pass it on and report the issues, enough is enough!!
https://www.fcc.gov/sites/default/files/obscene_indecent_and_profane_broadcasts.pdf
Thank you @CoffeeGoat the solution worked for me after a system restart (February 2023)
I found the best solution was to ditch Roku! Google TV offers a kid profile without ads and allows parents to protect adult profiles with a password. My kids no longer see nasty Roku ads and I tell everyone I know how much Roku sucks at protecting kids and providing family friendly content. They claim it can't be done. Google did it! I switched and couldn't be happier.
I agree with this post as well. there should be a way to set a rating for the ads and promos that pop up on the Home Screen. Lately, the promos have been nothing but scary movies or shows. This is a tv for use for the whole family. I see that this has been discussed on the board for years now....this is obviously something Roku should address .