In Bitcoin and Ethereum PoW, we have probabilistic BFT. I.e., the transaction finality will never reach 100%, but it will be very close to that with every further confirmation.
How about Geth POA Clique or Paritiy POA Aura? Is there a point in time where a transaction can be considered as 100% final.
For instance, in a Clique network with 3 sealers (S1, S2, S3), with the following block structure:
... Block #100 [TX1], sealed by: S1 (in-order -> block-difficulty:2) Block #101 , sealed by: S2 (in-order -> block-difficulty:2) ...
At Block #102: can I consider TX1 as being 100% final in a setting with 3 sealers?
At this point, it is impossible to present an alternative chain as long as 50%+1 sealers are honest (?)