The Russian invasion of Ukraine is partly to blame.
Image showing various windows for MSI Afterburner, an overclocking program for graphics cards.

MSI Afterburner has been one of the more popular tools used by users looking to overclock graphics cards. Despite being under the MSI branding, Afterburner was free to be used across all makes and models of GPUs, and helped everyone from gamers to professionals dial in the perfect overclock on cards from Nvidia and AMD.

MSI Afterburner was developed by Alexey Nicolaychuk, a Russian that is perhaps better known by his online handle of Unwinder. After Russia invaded Ukraine in early 2022, MSI stopped payments to Unwinder due to the obvious "political reasons," despite MSI hardware still being freely sold in Russia. Since then, Unwinder has continued to work on Afterburner development throughout the entirety of 2022 without any pay. His hope was that MSI would figure out some way to pay him, but that hope seems to have completely faded. Unwinder made a post on the Guru3D forums where he announced his unplanned retirement.

War and politics are the reasons. I didn’t mention it in MSI Afterburner development news thread, but the project is semi abandoned by company during quite a long time already. Actually we’re approaching one year mark since the day when MSI stopped performing their obligations under Afterburner license agreement due to “politic situation”. I tried to continue performing my obligations and worked on the project on my own during the last 11 months, but it resulted in nothing but disappointment; I have a feeling that I’m just beating a dead horse and waste energy on something that is no longer needed by company. Anyway I’ll try to continue supporting it myself while I have some free time, but will probably need to drop it and switch to something else, allowing me to pay my bills.
While Afterburner has been an important tool for overclocking graphics cards, it also allowed users to monitor a wide variety of statistics via an in-game overlay. This overlay was mainly powered by a separate component, RivaTuner Statistics Server (RTSS), that Unwinder also develops. He notes that while Afterburner development is coming to an end, he will continue to support RTSS. RivaTuner Statistics Server was always a separate component and piece of software that doesn't come with any sort of corporate ownership or branding.

While Afterburner should work for cards that are currently on the market, there is no saying if that will hold true for new cards that are coming out. There is also no saying whether or not a driver update for older cards will break Afterburner in the future without any sort of program update. Other popular overclocking software for GPUs have also been discontinued. EVGA used to have their Precision X utility that allowed for overclocking. However, with EVGA leaving the GPU market behind, that program was also discontinued.

For their part, MSI did release a statement about the situation. An MSI representative issued a statement to that we will share now.

Our product marketing & accounting team are dealing with this problem now. Due to the war, our payment couldn't transfer to the author's bank account successfully. We are still keeping in touch with him and figuring out how to solve this.
It's important to note here another bit that wccftech mentioned: There were recently a number of malicious Afterburner apps circulating around the web. These fake releases were full of malware that would infect users when they downloaded and attempted to what they thought was a legitimate release. With the official app currently stuck in a state of limbo, it's more important than ever that you keep an eye out for these fake releases that might try to resurface again. Only download applications from trusted sources.

Update (Jan. 9, 2023 at 5PM ET): In a separate statement issued to PC Gamer, MSI says that they "fully intend to continue with MSI Afterburner." It sounds like they plan to continue developing the application. Whether or not Unwinder will be involved in that future development still remains to be seen.

We fully intend to continue with MSI Afterburner. MSI have been working on a solution and expect it to be resolved soon.