Probably this PR: https://github.com/bitcoin/bitcoin/pull/29775

You'd have to pull the code in the PR and compile it yourself.

The reasons behind the attack on the v3 are not the Ordinals, the main fixes for V4 are two:

-Add Testnet4 difficulty adjustment rules fix.
-Add timewarp attack prevention for Testnet4.

I don't understand at all the technical side of the problem, but some people describe it as a block storm https://blog.lopp.net/the-block-storms-of-bitcoins-testnet/

And if you want to follow the current discussion about the migration, you can do it on the next link: https://groups.google.com/g/bitcoindev/c/9bL00vRj7OU/m/9yCPo3uUBwAJ

Looks like devs, aren't happy at all with the fact that Testnet has a value on markets, and they are even thinking about stopping the Testnet and only moving on with the signet. But I'm sure that will not happen, the community needs the testnet even if some people give it a bad use.

Some new devs decide take action into the bitcoin ecosystem and some of them are mining already have millions of Tbtc4 (even satoshi group wouldnt  do such thing), the real reason is centralize testnet . Tbtc3 will be online always, there is no possible way to shut down a blockchain with POW, many people will use Tbtc3 due huge distribution for more than a decade.

BTC is based in distribuid system with no central authority (no coder is the authority in BTC)
be aware of POW system that allow fix the problem of The Byzantine generals problem

the resent attack (spam, campaing etc) to testnet3 is a clear red flag in bitcoin development, but we well see  game theroy taking action in the recents events, after that, we can predict what is going to happens to BTC ecosystem in the future.

BTC was designed for a group of people we huge knowledges in cryptograpy, distribuid system, and economic laws. so is no about just to know code.

some programmners are touching the BTC code and changing it violating the balance in the system ignoring the knoledge about distribuid system and economic laws. and that is a huge concern in the futuere of BTC.

hope some of the first (expert  in (economists  and distribuid system) programmers  be aware of this.

code is easy, what is hard is the science behind BTC.

In case you want to run your own testnet4 node: i packaged everything in a container:

I did think it deserved it's own thread, since i guess other people might find it handy, and it's also still a work in progress
https://bt.irlbtc.com/view/5496494

Hi LoyceV,

Yup, you were right, you had to keep the top line, the bottom one is no longer needed.

It might be best to just use the container, i have it running on a demo machine and it works just fine... But if you want to try to build it on your local machine, you're always welcome to shoot me a quick PM (local language is fine, doesn't have to be in English)

I'm currently figuring out if i can build some kind of cpuminer in the same container and get it to work properly... cpumining might be long dead, it should still be feasible for testnet4.

PS: thanks for pointing out the typo, i'll fix it right away

The mining container is ready, it works, but (like you suspected) somebody is already running one (or more) asic's on testnet4.... why... i really wonder why.... why would you run an asic on a network that's designed to test ... why won't you let others get some tBTC to play with... At least, if you're nuking the testnet, create a faucet where others can have some tBTC to test out their setups...

If you need help with containers, let me know... But basically, if you trust what i've done, you could basically install docker and docker-compose on your system, make sure the docker daemon is running (on most linux distro's, a systemd service is created for you, you just need to enable and start it), then copy the content of the docker-compose.yml code block from this post (https://bt.irlbtc.com/view/5496494.msg64078200#msg64078200) into a local docker-compose.yml file, edit the paths, ports and passwords and execute "docker-compose up" (or "docker-compose up -d" to start in the background)

If you don't trust what i've done (i don't blame you), you could copy the first code block in  above post in a file called "Dockerfile" (you can check all steps), then run "docker build -t name_of_image:random_tag .". At this point, you'll have an image of your own in your local repo, and you can edit the image: tag in the docker-compose.yml file to point to your local image instead of mine.

I (finally) got it running! It took some fiddling with Mullvad VPN (for some reason it keeps blocking internet every time I create a new installation) and installing curl, autoconf, pkg-config, libtool, libc6-dev, build-essential and libboost-all-dev (thanks to other people with the same errors for recommending all those packages).
The result is a running bitcoind on testnet4. But there's no bitcoin-qt, which I kinda expected to be part of the default Bitcoin Core source compilation.
The total blocks directory is only 297 MB. This must be how Bitcoin felt in the early days.

Shortly after compiling it myself, I found bitcoincore.org/bin/bitcoin-core-28.0/test.rc1/, which has all the binaries already.