Try any US or UK government websites. Or try logging in or ordering something on BestBuy or HomeDepot. Many sites allow ordering but then cancel order next day (e.g. when processing by shop.app).
Instagram allows to open a profile either logged in or without a VPN.
When I argued that Google Cloud must have been blocking those already, they told me to provide some evidence (a written confirmation from GCP that they block the IPs), which is fair.
Some used to mess with DNS. Others used to use packet inspection.
Personally I’ve not experienced any blocking, probably due to DoH.
For example in Russia it's common knowledge nowadays to the extent that babushkas discuss relative merits of various VPN services while gathering shrooms in the woods.