Not sure of the intended behaviour here but as Spectator mode doesn't apply the full screen overlay effect when inside a block in Spectator it seems odd that it would do so here, as it does have slight detrimental effects on the player's vision which should not happen in Spectator.
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clones 1
discovered while testing 1
is duplicated by 1
testing discovered 1
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Can confirm in 21w06a.
Can confirm in 21w07a.
Can confirm in 21w08b.
Can confirm in 21w13a.

Can confirm in 1.17.1.
Can confirm in 1.18.1.
Can confirm in 1.18.2.
Can confirm in 1.19 and 22w24a.
Can confirm in 1.19.2.

Can confirm in 1.21.3.
Can confirm