This thread was helpful in solving two problems I had with Raspbian Buster:
The first was a Pi updated to Buster. It had libssl and libcrypto files for 1.1 and 1.0.2, as well as a symbolic link from libcrypto.so to 1.1. Renaming the link out of the way solved that problem. (Hopefully without breaking anything else.)
The second, with a fresh install of Buster, only had the 1.1 libs. sudo apt-get install libssl1.0.2 fixed that.