As far as I know, the lightning channel itself in blockchain is an P2WSH (https://learnmeabitcoin.com/technical/script/p2wsh/) address UTXO with a 2-of-2 multisig script in it. Closing channel transaction is just spending from this UTXO.
For example: this transaction closed channel of 0.01 btc between two parties, Alice got 0,00032957 and Bob got 0,00965581
Are there another implementations of lightning channels, not P2WSH? I saw several transactions in blockchain, which are very similar to LN, but the difference is that the channel is not P2WSH, but P2TR eg :
https://mempool.space/tx/acf77ab7ab071013e5202b76b019db6ea12760383c51a7f654f4b52e568831ec
https://mempool.space/tx/491157017cb0925b6ab94ad30beaa623f01e928827cea09cd94bc6918b593830
https://mempool.space/tx/be823f6c623de60556a353e2f644a790dca28d9118c45e8f117ba82b99acc5ed
Reply:
As you mentioned, there are Taproot (P2TR) channels, normally called Simple Taproot Channels (https://bitcoinops.org/en/topics/simple-taproot-channels/).
Since v0.17-beta, LND supports P2TR on the Lightning Network. LND is also working on a project called Taproot Assets, which relies on Taproot. This feature is already usable and essentially allows you to issue and transfer assets (other than BTC or sats) using the Lightning Network.
To the best of my knowledge, CLN does not support Taproot channels yet. However, it does allow the generation of P2TR addresses for the on-chain wallet.
Similarly, ACINQ does not support Taproot channels either. However, they use Taproot in Phoenix for a feature called Swaproot (https://acinq.co/blog/phoenix-swaproot), a swap-in/swap-out protocol that facilitates deposits and withdrawals from Phoenix using Taproot.
Note that other pre-segwit address types, like P2SH cannot be used due to Transaction Malleability (https://bitcoin.stackexchange.com/questions/69317/why-was-transaction-malleability-fix-required-for-lightning-network) so only P2WSH and P2TR are used for the Lightning Network.
So, to answer your question: Lightning channels are not always P2WSH. While P2WSH remains the most common format, LND has introduced support for P2TR channels, so most P2TR channels you may encounter are likely between LND nodes, as CLN and ACINQ have not yet implemented them.