Can we still follow users via the API?

API
2

You didn’t include the v5 header, so it tried to use the v3 API

Requests
For client IDs created on or after May 31, 2019, the only available version of the Kraken API is v5.  For client IDs created prior to May 31, 2019, use the application/vnd.twitchtv.v5+json header on your requests to access v5 of the Kraken API.

curl -H 'Accept: application/vnd.twitchtv.v5+json' \
-H 'Client-ID: uo6dggojyb8d6soh92zknwmi5ej1q2' \
-H 'Authorization: OAuth cfabdegwdoklmawdzdo98xt2fo512y' \
-X PUT 'https://api.twitch.tv/kraken/users/44322889/follows/channels/129454141'

You need the Accept header and you have not included it

Or migrate to helix

Get Follows:

Create/Delete