The developer mononaut has released some data looking at 5000 blocks since mining pools started including below 1 sat/vByte transactions in the blocks they mined. Whether all of this is accurate or not, I don't know, but this is what he says:

- Until block 915000, pools have mined a total of 9,002,455 below 1 sat/vByte transactions in a total of 4743 blocks.
- They have earned an additional 7.49 BTC in transaction fees while doing it.
- They used 1951 MvB of extra block space.

One dilemma was if including these low-fee-paying transactions in blocks would increase the risk of stale blocks.
Apparently, MARA has reverted back to a fee relay of 1 sat/vByte for the blocks they mine out of fear of mining stale blocks because many other pools also lowered their minimum fee rates.

According to mononaut, there were only 3 stale blocks in the last 5000 mined blocks, and they weren't caused by below 1 sat/vByte transactions. mononaut concludes that it made sense to lower the minimum fee rates. The miners earned a bit more in fees without increasing the average number of stale blocks.

You can read his thoughts on this topic below:
https://x.com/mononautical/status/1968138301182972400