The fact that in Bitcoin we took the time to fully think through, write a clear and complete specification https://github.com/bitcoin/bips/blob/master/bip-0152.mediawi... , and thoroughly test and review the implementation before deploying it while BU has been occasionally abused by the BU organization and their supporters to dishonestly claim that compact blocks came later (or were somehow derived) from their work.
Users on the sidelines were easily deceived by this marketing because BU rushed their implementation into production while Bitcoin took a more deliberative process.
BU's "thinblocks" implementation was, in fact, severely flawed both due to an implementation vulnerability that resulted in almost every BU node on the network being crashed near simultaniously, and due to a design error introduced because BU's "chief scientist" strongly believed that it was computationally intractable to produce a collision in the first 64-bit of transaction IDs (a sha2 hash), even though one can be computed on a fast desktop computer in seconds.
So the history is that: Bitcoin developers proposed and tested an idea for faster block propagation using filters and found it lacking. Later, it came up again as a possible way to mitigate segwit's bandwidth increase, so I wrote a design to address the known issues and we started working on implementing it. A few weeks later BU developers picked up the old work and started improving it. Within a couple months they had it deployed it in public and announced 'mission accomplished', but their deployment was unspecified and ultimately faulty. As a result of those issues and the superior relay latency of compact blocks thinblocks was replaced in the Bitcoin Cash network with the protocol from Bitcoin.
There is no common protocol feature in BU's xthinblocks that wasn't also in Bitcoin's original work that inspired both efforts. There could have been no influence on compact blocks' design by xthinblocks because it would have been physically impossible for there to be due to causality. That hasn't seemed to stop BU developers and people like you from repeating this lie.
The original design document for compact blocks is was published (and last modified) on Dec 25, 2015. https://people.xiph.org/~greg/efficient.block.xfer.txt
The earliest work for Bitcoin Unlimited's "Thin Blocks" was on Jan 10th 2016: https://bitco.in/forum/threads/buip010-passed-xtreme-thinblo...
Both were motivated by an earlier effort by Bitcoin developers Matt Corallo and Pieter Wuille, https://buildingbitcoin.org/bitcoin-dev/log-2013-12-27.html#... (which Pieter had implemented, but was found to not work so well, https://buildingbitcoin.org/bitcoin-dev/log-2013-12-28.html#...).
The fact that in Bitcoin we took the time to fully think through, write a clear and complete specification https://github.com/bitcoin/bips/blob/master/bip-0152.mediawi... , and thoroughly test and review the implementation before deploying it while BU has been occasionally abused by the BU organization and their supporters to dishonestly claim that compact blocks came later (or were somehow derived) from their work.
Users on the sidelines were easily deceived by this marketing because BU rushed their implementation into production while Bitcoin took a more deliberative process.
BU's "thinblocks" implementation was, in fact, severely flawed both due to an implementation vulnerability that resulted in almost every BU node on the network being crashed near simultaniously, and due to a design error introduced because BU's "chief scientist" strongly believed that it was computationally intractable to produce a collision in the first 64-bit of transaction IDs (a sha2 hash), even though one can be computed on a fast desktop computer in seconds.
In fact, Bitcoin Cash developers went so far as to attempt to block the deployment of compact blocks by falsely claiming that it would somehow "disrupt the network": https://www.reddit.com/r/btc/comments/4xkqbk/core_intends_to... (It didn't.)
So the history is that: Bitcoin developers proposed and tested an idea for faster block propagation using filters and found it lacking. Later, it came up again as a possible way to mitigate segwit's bandwidth increase, so I wrote a design to address the known issues and we started working on implementing it. A few weeks later BU developers picked up the old work and started improving it. Within a couple months they had it deployed it in public and announced 'mission accomplished', but their deployment was unspecified and ultimately faulty. As a result of those issues and the superior relay latency of compact blocks thinblocks was replaced in the Bitcoin Cash network with the protocol from Bitcoin.
There is no common protocol feature in BU's xthinblocks that wasn't also in Bitcoin's original work that inspired both efforts. There could have been no influence on compact blocks' design by xthinblocks because it would have been physically impossible for there to be due to causality. That hasn't seemed to stop BU developers and people like you from repeating this lie.
Cheers.