Can someone explain these strange transactions?

[Phobos_Quake]

I was looking at the mempool graph and I noticed a lot of transactions squares of the same size, the next  day the same thing.
I went to look at these addresses and they do A LOT of transactions per minute to their own account, with very small fee.

https://www.blockchain.com/explorer/addresses/btc/bc1qpp6zv89vgh3w9qn4d38k7fg0cxpqeev0cc33w5

https://www.blockchain.com/explorer/addresses/btc/bc1qzug6vpazdrxern6yx8tysu9aulh387n8l4sr7l

https://www.blockchain.com/explorer/addresses/btc/bc1q992d3v7xrz4vuuw974scqffu8lna98elhxhqyd

https://www.blockchain.com/explorer/addresses/btc/bc1qe4x8k8m5gwwhvn005tmsyj65ks83s9psmu9nrk

What are they doing?

[MarryWithBTC]

This is a pattern but it is unlikely to be a spam for profits because the fees are ridiculously low and nether is it an attack.
It is looking like an automated bitcoin activity, generated by software because humans can't send repeated identical transactions per minute with the same structure, almost identical size and timing.

I showed this to my friend, he was of the opinion that someone is washing bitcoin in a traditional way. But I didn't actually understand his explanation because they are sending to their own addresses.
If the goal were obfuscation, you will expect coins to move across many unrelated addresses.

Sending coins back to oneself is commonly about UTXO management, fee optimization or for testing automated systems.

[Phobos_Quake]

Seems unlikely to be UTXO clean up because the transactions are very small.

They did transfer to another account at some point, I've seen these accounts have above $20k at least at some point, now some are empty.

For laundering seems silly, since there are AI tools now that can follow the money pretty easily.

[LoyceV]

It's "Runestone" spam, see mempool.space.

[Phobos_Quake]

It's "Runestone" spam, see mempool.space.

What does that mean?

[BitMaxz]

What does that mean?

That's an ordinal inscription; it looks like an NFT in the ERC20 or Binance/Ethereum network.
It's a collectible thing behind the Bitcoin network.

You can buy them or sell them on MagicEden, and based on Coingecko they only have a Discord community.
Check them here: https://www.coingecko.com/en/nft/runestone

About this: https://www.xverse.app/blog/runestone-ordinals

[FinneysTrueVision]

This is the overview for the first address. You can see that they have made over half a million transactions and a lot of that activity is related to inscriptions. Those inscriptions are just data added to transactions to represent tokens on the Bitcoin blockchain.