Youtube unfortunately have deactivated all comments under kids' videos...no way for parents to share feedback anymore. So in case anyone looks here:
The Gecko's Garage up to about 2018 was great: it featured lots of interesting mini-documentaries with footage & interviews about real-world vehicles and other mechanical transports. It was charming, educational, didn't grate, had catchy songs...my toddler was hooked. The 2D cartoony graphics are basic but do the job fine.
At some point I noticed there was a change in style: now it's all full-on CGI 3D graphics, with slapstick stories about over-the-top vehicular-calamity scenarios. There's no real-world footage anymore, the documentary-style and learning-exercises are gone. Post-2018 there's now a regular antagonist (a buffoon-type who's always out to sabotage Gecko), and not-so-subtle pro-woke messaging. Whatever your stance on trans-dressing, Pride marches and children with lesbian mothers (no father figures)...I'm sure we can all agree these aren't suitable themes for toddler entertainment.
The other important thing to note is that over the last few years Toddler Youtube channels have become incredibly lazy: i.e. Automated. Instead of uploading a single video (say 5-20min long) with a coherent narrative, the channels now upload hour-long 'compilations' which are randomly-edited (probably by bot-scripts). This means if you're not supervising, your toddler will watch stories suddenly stop right in the middle of their narrative, and cut to the middle of a totally different 'episode'. This can't be good for learning! Even the official channel for Peppa Pig is doing this. And as Youtube deactivated comments there's no way to feedback on it.
Regarding Gecko's Garage: if you stick to the official "Toddler Fun Learning" account for uploads from 2015-2018 then there's a lot of good toddler content, with clear narratives.
From 2019 you only get the CGI-cartoon stories, woke-messaging and lots of long jumbled-up single videos with multiple incomplete episodes.