I see. In [order to transact with those assets on lightning one would need to have an LND node plus some software][1]. But taproot assets can also be sent onchain.]
I would like to know if there is way to apply filter to transactions both issuing and moving them onchain.
  
[1]: https://docs.lightning.engineering/lightning-network-tools/lightning-terminal/integrating-litd 

denationalized

mempool

How do I stop my lightning node from propagating USDT and other taproot assets?

No, there's no way to filter because the tapass are not like sats "traveling" around channels. Are just tokens created at the initial channel and "decyphered" at the destination peer.
And is working only with nodes that use the LiT (Lightning Terminal). LiT is the "interface" for these tapass.

Is like the comment attached to a LN invoice.

The only way to stop this crap is to educate more people to not use them.