I don’t see the problem.
Those heavy talks shouldn’t always be a big deal. We shouldn’t only talk to our kids about feelings or emotions when they are upset.
The message should be dripped in as often as possible in my opinion, it should be normal to see those messages. When it is normalised, kids won’t be triggered every time someone says it’s ok not to be happy all the time or that it’s ok to feel sad.
Accepting their feelings, good and bad, should be as natural as breathing rather than feeling like there’s something wrong with them if they’re not happy.