Coverage of the finals is usually much less detailed, unfortunately, since the number of teams is much smaller and the challenges don't necessarily go up. However, https://oooverflow.io/dc-ctf-2020-quals/ has a couple more writeups linked from it; https://dttw.tech/posts/SJ40_7MNS#proof-by-exhaustion from PPP and http://www.secmem.org/blog/2019/08/19/Shellcoding-and-Bitfli... from SeoulPlusBadass.
Binary bitflip resilience is really cool. The radiation-hardened-quine idea (https://codegolf.stackexchange.com/questions/57257/radiation..., https://github.com/mame/radiation-hardened-quine) is cool, but these source-based approaches depend on a perfectly functioning and rather large (Ruby, V8, whole browser) binary stack. A bitflip-protected hex monitor or kernel, on the other hand...
Coverage of the finals is usually much less detailed, unfortunately, since the number of teams is much smaller and the challenges don't necessarily go up. However, https://oooverflow.io/dc-ctf-2020-quals/ has a couple more writeups linked from it; https://dttw.tech/posts/SJ40_7MNS#proof-by-exhaustion from PPP and http://www.secmem.org/blog/2019/08/19/Shellcoding-and-Bitfli... from SeoulPlusBadass.