Per Jeff's debugging, it seems `backdrop-filter: blur(3px) on .b-needle::after` causing this issue.
Bug 1896948 Comment 12 Edit History
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Per Jeff's [debugging](https://matrix.to/#/!wbEUPKmXGxodKqLlZL:mozilla.org/$-M1iicPtQNFkCyXF6R5v1E36hCq8yUFDYbJyaX2e5lI?via=mozilla.org&via=matrix.org&via=igalia.com), it seems `backdrop-filter: blur(2px) on .b-needle::after` causing this issue.