j"19HxigV4QyBv3tHpQVcUEQyq1pzZVdoAutLæTBH, I don't know. I'm not sure it matters, so long as the transactions end up on chain within a reasonable amount of time.
I'd suspect they maintain their own DB, considering twetches exist in twetch before inclusion in a block.
text/plaintext twetch_twtext_1590519885784.txt|"1PuQa7K62MiKCtssSLKy1kh56WWU7MtUR5SET twdata_jsonnullurlnullcommentnullmb_user622reply@de39de974f8fd4a649b3e50db319b431e7d783758cce16bec9f90525c1483ad7typepost timestampnullapptwetchinvoice$a05e5ccd-1f6f-45d9-90e6-c8c3a6b9f7c7|"15PciHG22SNLQJXMoSUaWVi7WSqc7hCfva
BITCOIN_ECDSA"1Eyk15KEeYX9JwH8e98pqpX3kTUuY9d43CLXHzlQHfIGknfHeYIOQGFQgdTD6hFDeEWowTpnmFG1hAmTeT6TPEeWi9fzneBvoiDHePRzXBr7bfWJDdNOeKAj0lE=
https://whatsonchain.com/tx/ea3c092296767efb5d04ea10ca6f798f793f75800942857a34881e360a3cce2b