Thank you. I tried all the explorers.

The transaction was not found apparently on:

https://btc.cryptoid.info "no matching results"
https://www.blockonomics.co "transaction not found"

However, I could find it on:

https://mempool.space
https://bitaps.com
https://blockstream.info/
https://www.blockchain.com
https://blockchair.com
https://btc.com
https://chain.so
https://bitpay.com
https://live.blockcypher.com

Is 2 enough to assume that the transaction was dropped by the network? I am asking, however I must say, I actually tried to re-send the UTXO (not sure I am using the term correctly) 9 days ago. To do so, I resynced the SPV of the wallet of the exchange following a conversation there: https://bisq.community/t/2-month-old-btc-withdraw-shows-as-local-in-electrum/12517/2?u=cks. The re-send though is still pending (as of now) for confirmation in the wallet of the exchange. The interpretation of a user of that exchange is that the previous transaction is still "traveling through the network" https://bisq.community/t/2-month-old-btc-withdraw-shows-as-local-in-electrum/12517/10?u=cks.

I noted the comment of BitMaxz, who wrote "if you can't find this TXID on some blockchain explorer it means it's already rejected by some nodes you should now be able to re-send it." - but the transaction was not found on 2 explorers, however the re-send is still "not found" by mempool.space.

I am thinking then I should try to change server, and see if a server can pick up the transaction again, but I am not sure.

What do you think?