I didn't want to claim that Telegram's crypto was better or as good as Signal's. But saying that Telegram rolled their own crypto while Signal did not is misleading as both designed their own protocols.
Also, Telegram uses SHA256 now in the places relevant for security, so that point was resolved.
Telegram's crypto is reportedly designed from scratch, with questionable choices such as SHA1 and MAC-then-encrypt.
https://www.cryptofails.com/post/70546720222/telegrams-crypt...
https://eprint.iacr.org/2015/1177.pdf