I hope they fixed that issue once and for all, but I really don’t know.
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Instead you can create and use a group device for switching multiple lights.
You can use Device Capabilities or < group > app for this. They switch the lights in a group device in sequence automatically, which means ‘not all at once’. -
In advanced flow, you can ‘daisy-chain’ the lights, then they’re switched on/off in sequence. This is almost not much more work, than adding them in parallels