Tumblr has spread a bunch of misinformation about what losing Net Neutrality actually brings.
You’re not going to get blocked from Tumblr. You’re not going to lose your internet as you know it today. Nothing HAPPENS yet.
If CONGRESS approves the repeal (which will be held on a separate court date, NO action will be taken until then) tumblr may become slowed down for you. That all depends on what tumblr itself is willing to pay. You still have access; it just may become limited.
It’s still something you need to push against and be aware of, but there’s no need to hand out phone numbers just yet. Call your representative, let them know you support Net Neutrality, and keep an eye on the court date.