[Bug] Memory leak when tooltip with <img> is used: loaded file is not unloaded, memory usage increases indefinitely

[mdav43]

Describe the bug
When a tooltip or popover contains a URL (e.g. on the tooltip), the loaded resource is not unloaded when the tooltip is closed. Repeatedly opening and closing such tooltips causes memory usage in the browser (Safari/macOS) to increase indefinitely, eventually leading to excessive memory consumption.

Context: I use an external service to serve images and videos from an iPhone in the tooltip. Apologies, I used copilot to draft this ticket when looking at the map-popover file (I'm not a typescript programmer).

To Reproduce
Steps to reproduce the behavior:

1. Go to a kepler.gl map on macOS Safari
2. Hover over a map feature to display a tooltip containing an image, video, or iframe loaded from a URL.
3. Close the tooltip/popover.
4. Repeat steps 2–3 multiple times (depends on the resource size) started as soon as I loaded a few videos.
5. Observe memory usage in Safari Web Inspector or Activity Monitor. Memory grows steadily with each cycle; resources are never released.

Expected behavior
When the tooltip/popover is closed or unmounted, any loaded resources (iframes, blob: URLs, images, videos, etc.) should be properly unloaded and released, so memory usage returns to baseline.

Screenshots
N/A (Observed with memory/heap growth in Safari Web Inspector and Activity Monitor)

Desktop (please complete the following information):

• OS: macOS
• Browser: Safari
• Version: (latest)

Additional context

• Reference implementation where leak occurs: src/components/src/map/map-popover.tsx
• Root cause: resources loaded inside the tooltip (iframes, blob URLs, media files) are not explicitly unloaded when the popover closes or unmounts. Browsers may keep these resources alive if not explicitly revoked/unloaded.
• Suggested remediation: On popover close/unmount, explicitly unload embedded resources by setting iframe src to 'about:blank', revoking blob: URLs, and detaching DOM nodes. Run cleanup before calling parent's onClose and also in the unmount effect. See conversation/code for details.

[igorDykhta]

@mdav43
How can I reproduce this?
Do you have a dataset?
I’m not sure how to add images to tooltips.
Just using URLs or tags doesn’t seem to work in a csv file