Giving gratitude is positive sum.
Some people see gratitude as zero sum.
To them, if someone gives gratitude to the other person, that implies that the net value transfer is from the other to them.
But you can both give gratitude!
Gratitude can flow both ways, for different things.
The more authentic gratitude you give, the more you build the relationship of trust and mutual respect.
When someone makes you feel appreciated, it's a vaccination that preps you to receive criticism and not feel like it's an existential danger.
It builds up your resilience battery.
So when in doubt, give gratitude!