Thucydides says that some victims of the plague lost fingers, toes and genitalia.
“[8] κατέσκηπτε γὰρ ἐς αἰδοῖα καὶ ἐς ἄκρας χεῖρας καὶ πόδας . . .”
Perseus edition 1.49.8.
Has there ever been any suggestion, or is there any evidence, that Thucydides himself suffered one or more of such losses?
No. All we know is what Thucydides said, which is that he also experienced the plague.
But historians do think that they know something about Gibbon’s aidoiicotal affliction.
It occurred to me that writing, editing and correcting a manuscript would be difficult for a man without fingers. But that would presuppose that Thucydides wrote his own notes and work rather than dictating it. To be sure, not having fingers (or toes) would not prevent him from holding a command.