Not celebrating is a cultural issue. Even if you ship a thousand new things a week, you can still take time to celebrate those. It's your (or your team's) choice not to.
One good example is Linear. The product improves day by day, but they also publish a regular (weekly) summary of the changes. And for me as a user it's a delight to read through them. https://linear.app/changelog
I don't think a client-facing changelog tells us much at all about how the dev-team celebrates.
Calling it a cultural issue seems off. Perhaps in some cases it is. But if the process truly is a grind, then the only target left to celebrate might be a proxy metric that the devs don't relate to. (Congrats on staying within 0.5 sigma of our mean time to deliver this week, let's have a pizza.)
Celebrating doesn't have to be a reward, and assuming that celebrating a release involves a material reward is certainly cultural. To me, the important part of celebrating a release/milestone is pausing and reflecting on what has changed. That only needs to be a small nod.
