Yep, already pointed that out. And there’s no ifs, it is a new rule. As Awaywego mentioned, FA Cup rule 95 now states:
“A Player shall only play for one Club in the Competition during the same Season, save that a Player that has played for one Club in the Qualifying Competition and/or the Competition Proper may play for a maximum of one other Club in the Competition Proper (but may only play for a maximum of one Club in any given round of the Competition).”