this website is called "arweave app explorer": https://explorer.arweave.co/

can be hard to find those sometimes

viewblock, a block explorer, is onchain: https://wrqt7rptepcvuyxcu47ovrksdhpct3nb26vc3t653grfqj7g6hua.arweave.net/tGE_xfMjxVpi4qc-6sVSGd4p7aHXqi3P3dmiWCfm8eg

says the tip block is 870708 lR94WAWPp07Ckz521Rem5q7P1rYEySgOERZKshYWsTzmcQAWZ3HUNgDTmjS8FSci