Multi-scene worlds SDK UI appears in wrong scene

The UI from scenes that are not the current scene has been seen appearing randomly regardless of the current scene.

The only place I can actually 100% repro rate be able to reproduce it is in the multi-scene world used to test sdk7-test-scenes, you can access there following these instructions:

1. Switch MetaMask to the **SEPOLIA** network (not mainnet)
2. Open the Explorer using one of these methods:
- **Deep link** (any browser): `decentraland://?dclenv=zone&realm=sdk7testscenes.dcl.eth&position=75,-9`
- **Custom build**: launch with `--dclenv zone --position 75,-9` app params — [instructions](https://github.com/decentraland/unity-explorer/blob/main/docs/how-to-connect-to-a-local-scene.md#connecting-a-custom-build-to-the-scene)

https://github.com/user-attachments/assets/6ca1156d-db1a-4139-9827-6d0a00041eb9

NOTEs:
* I have also see this happening in the `italy2026.dcl.eth` hackathon multi-scene world (but not 100% repro like the `sdk7testscenes.dcl.eth` one)
* This has been reported for the first time by a user happening in the multi-scene world `antela.dcl.eth` on April 6th 2026 ([thread](https://decentralandteam.slack.com/archives/C0292P4HJ93/p1775501415697899)).

Reproduce the issue in the sdk7-test-scenes multi-scene world using the SEPOLIA network and the provided deep link or custom-build parameters. Trace how UI from non-current scenes is displayed, then verify that only the current scene's UI appears and retest the italy2026.dcl.eth case if available.

Written by the indexing model from the issue text.