I need to clear up a common misconception. If a manga adaptation ends, it's not because it was just an ad for the LN source material. It means that it sold so poorly that the publisher didn't want to continue investing in it anymore. Light Novels are a much smaller niche than manga, so publishers are actually more lenient on manga sales than LN sales. Many dead light novel series have ongoing manga adaptations because it's easier to sell them than the original LNs are.
The LN itself is pretty clearly axed at 2 volumes as of 2022. So chances are that the series as a whole just sold so poorly that they dumped it.