Is it "just" that, or is it Elsevier's, Wiley's, and friends' doing? As I had commented the other day on a same/similar post, One Nation One Subscription was signed with Wiley this February, maybe other publishers have done something similar.
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.
Some used to mess with DNS. Others used to use packet inspection.
Personally I’ve not experienced any blocking, probably due to DoH.
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.