Fix visibility filter on explore projects

app/finders/projects_finder.rb

@@ -131,7 +131,7 @@ class ProjectsFinder < UnionFinder
 
     public_visibility_levels = Gitlab::VisibilityLevel.levels_for_user(current_user)
 
-    !public_visibility_levels.include?(params[:visibility_level])
+    !public_visibility_levels.include?(params[:visibility_level].to_i)
   end
 
   def owned_projects?

changelogs/unreleased/fix-explore-projects-by-visibility.yml

+---
+title: Fix visibility filter on explore projects page
+merge_request: 58293
+author: Jonas Wälter @wwwjon
+type: fixed

spec/finders/projects_finder_spec.rb

@@ -129,6 +129,12 @@ RSpec.describe ProjectsFinder do
 
           it { is_expected.to eq([public_project]) }
         end
+
+        context 'as string' do
+          let(:params) { { visibility_level: Gitlab::VisibilityLevel::INTERNAL.to_s } }
+
+          it { is_expected.to eq([internal_project]) }
+        end
       end
 
       describe 'filter by tags' do