Sorry about that, but I think I accidentally clicked the button. Anyway...
You installed the 7.83.1-2.1 version which is the one broken because of the wolfssl security update. If you can't see a higher version in the releases for your archi, you need to downgrade to 7.83.1-1 versions for now.
curl - 7.83.1-1
libcurl4 - 7.83.1-1
To do this (excerpt from here: https://github.com/openwrt/packages/issues/19547#issuecomment-1271809668)
Until it's fixed you could use the archive repo:
https://archive.openwrt.org/releases/
https://archive.openwrt.org/releases/21.02.3/packages/x86_64/packages/ e.g.
and download these packages which aren't affected:
curl - 7.83.1-1 (packages)
libcurl4 - 7.83.1-1 (packages)
libwolfssl5.2.0.99a5b54a - 5.2.0-stable-2 (base)
e.g. for 21.02 x86_64 - step by step: (with typo corrections)
wget -q https://archive.openwrt.org/releases/21.02.3/packages/x86_64/packages/curl_7.83.1-1_x86_64.ipk
wget -q https://archive.openwrt.org/releases/21.02.3/packages/x86_64/packages/libcurl4_7.83.1-1_x86_64.ipk
wget -q https://archive.openwrt.org/releases/21.02.3/packages/x86_64/base/libwolfssl5.2.0.99a5b54a_5.2.0-stable-2_x86_64.ipk
opkg install libwolfssl5.2.0.99a5b54a_5.2.0-stable-2_x86_64.ipk
opkg install libcurl4_7.83.1-1_x86_64.ipk
opkg install curl_7.83.1-1_x86_64.ipk
^^^ NOTE: I corrected the above as the instructions in the comment in github is incorrect.
You might need to also do --force-reinstall if it won't downgrade the package.