With @jancernik we merged a few fixes today that should address this issue on iPad.
- FIX: Remove scroll events for mobile modals (#29391) · discourse/discourse@ed40c8b · GitHub
- FIX: Enable scroll events in modals for IOS (#29393) · discourse/discourse@0983e73 · GitHub
- FIX: remove redundant body scroll lock (#29395) · discourse/discourse@9b1c6f8 · GitHub
Let us know if you can still reproduce the issue. (Or if the fixes cause other problems.)