The opcodes in bold are unstable. Only 2 of those 7 opcodes ($8B, $AB) are actually unstable in the sense that they may produce a truly unpredictable result. The other 5 opcodes actually produce predictable results – but the conditions under which they do that and the produced results are a bit unexpected.
{| class="wikitable" style="white-space: nowrap;"
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! rowspan=2|Mnemonic !! colspan=10|Addressing Modes !! colspan=8|Flags !! rowspan=2|Operation !! rowspan=2|Description