I reacted to an issue in GitLab issue tracker with thumbsup. Inside the issue i can see my reaction. Visiting Issues / List i can also see that the issue has an upvote. I can see reactions from others as well.

The problem: Visiting the Site in private mode as unregistered visitor it is different. The difference is inside the issue, where i can no longer see the reaction i placed earlier (when logged in).

The issue in question: bug: target_sources generator expression when target in other directory (#22774) · Issues · CMake / CMake · GitLab

The question: how can i make others / unregistered user see my reaction?

You can try maybe under project settings → General → Visibility, project features, permissions and change issues from project members to everyone with access. Not sure if that will help or not, but I also notice on gitlab.com for some projects with similar behaviour in that the votes cannot be seen unless you are logged in. So there is every chance, that this will not help you, and if not, I cannot see any option that allows this to be changed and if that is the case, then it’s not possible.