Working as expected
Did not notice any bad visible side-effect for several months of usage.

It has allowed me a new way of browsing. Keep everything that could have a high background load/misbehave in tab groups so that they can easily be unloaded by collapsing the group.

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In that specific use-case to "quickly reduce CPU usage by collapsing tab group", a shorter configurable timeout would be beneficial, but that's just QoL detail.