Short Tl;DR version: It appears that Youtube is depecrating the 'relatedToVideoId' search type in their API as of August 7th, 2023 and I'm trying to find a replacement solution to get related videos from a supplied video ID.
https://developers.google.com/youtube/v3/revision_history#june-12,-2023
Long version: Currently working on a YT embedded player based client largely written in HTML/CSS/JS with some backend PHP stuff in the mix. One of the key features I need implemented is a way to retrieve related videos for a currently playing video. Up until re-reviewing the API docs this morning, everything was planned out and looked like it was completely doable. However it looks like this deprecation announcement was just recently added and there seems to be no mentioned replacement functionality.
In an ideal world, I'd love to have a local database with all the video info (likely using the YT API, scrape an entire channel's uploads and store all the data/info/tags into a local DB I can then query without expending API quota) but replicating Google/YT's related video algorithm is likely going to be a huge pain.
Ultimately I'm just trying to figure out what my options are going forward. This feature is just about make or break for this project sadly.