I'd be interested to know if there's a way to fix this issue with extensions. Do you mean browser extensions? I use a browser sometimes and newpipe sometimes.
Using a browser and ublock origin, I find viewing youtube to work ok except for the occasional age gated video that I can't view without a google account. What's stopped working is search ordering and seeing timestamps. Like old comments might get labelled "2 years ago" with mouse-over no longer showing the actual date/time. It's not shown in the unrendered HTML in any obvious way either.